The US embassy in the UK and the Foreign Office have issued seemingly contradictory advice about whether UK residents with dual nationality are "apparently exempt" from President Trump's US travel ban.
On Sunday, the Foreign Office said they were exempt, provided they are not travelling from one of the seven banned countries.
The Foreign and Commonwealth office said:
The Presidential executive order only applies to individuals travelling from one of the seven named countries.
If you are travelling to the US from anywhere other than one of those countries (for instance, the UK) the executive order does not apply to you and you will experience no extra checks regardless of your nationality or your place of birth.
If you are a UK national who happens to be travelling from one of those countries to the US, then the order does not apply to you – even if you were born in one of those countries.
If you are a dual citizen of one of those countries travelling to the US from OUTSIDE those countries then the order does not apply to you.
The only dual nationals who might have extra checks are those coming from one of the seven countries themselves – for example a UK-Libya dual national coming from Libya to the US.
On Monday a statement on the US embassy's website warned the issuing of visas had been "suspended effective immediately until further notification" for dual citizens from the seven nations.
A UK diplomatic source later told ITV News Deputy Political Chris Ship the Foreign Office advice trumped the US State Department.
The source said the Foreign Office's advice was cleared at the highest levels of the White House.
Foreign Secretary Boris Johnson spoke directly on Sunday to President Trump's son-in-law Jared Kushner, who is a member of Mr Trump's inner circle.
It came after a New York judge issued an emergency order temporarily barring the US from deporting people with valid visas who were affected by President Donald Trump's travel ban.
Mass protests erupted after Mr Trump banned refugees and people from seven Muslim-majority countries from entering the US.
Here we explain how the situation unfolded, who is affected and what happens next.
The executive order
Donald Trump signed an executive order on Friday which he said was aimed at keeping "radical Islamic terrorists" out of the US.
The order banned refugees from Syria arriving in the US indefinitely and put a 90-day ban on entry to the US to all citizens from seven Muslim majority nations: Iraq, Syria, Iran, Sudan, Libya, Somalia and Yemen.
It also covered anyone with an approved refugee application.
Many have questioned Mr Trump's motives, as a report by Cato Institute found that between 1975 and 2015 foreign terrorists from those seven countries killed zero Americans on US soil.
The directive did not do anything to prevent attacks from homegrown extremists who were already in America, a primary concern of federal law enforcement officials.
It also omitted Saudi Arabia, home to most of the 9/11 hijackers.
Under Trump's order, it had appeared that a number of foreign-born US residents now travelling outside the US could be stuck overseas for at least 90 days even though they held permanent residency green cards or other visas.
However, an official with the Department of Homeland Security said on Saturday night that no green-card holders from the seven countries cited in Trump's order had been prevented from entering the country.
In December 2015, Donald Trump declared all Muslims should be stopped from entering the United States until officials understand where their "hatred" for Americans comes from.
The then Republican Presidential candidate said the hatred was "beyond comprehension" and that there should be a "total and complete shutdown" until authorities figure out "what is going on".
Five months later, he backtracked on his proposal saying it was "only a suggestion".
Last night, Mr Trump told reporters his latest executive order was "not a Muslim ban".
Reaction to Trump's executive order
Iran said it would take "reciprocal measures" against the US in retaliation for the visa ban put into effect by President Trump's executive order.
Iraq's foreign affairs committee said the US travel curbs imposed on Iraqis were "unfair" and asked the government in Baghdad to "reciprocate" to the American decision.
Two Iraqi MPs who declined to be identified said the country is to argue with the US that travel curbs on its citizens could affect co-operation in the war on so-called Islamic State.
The prime minister of Canada, Justin Trudeau, attacked Mr Trump's decision, declaring: "To those fleeing persecution, terror and war, Canadians welcome you, regardless of your faith".
Mr Trump's US election Democratic rival Hillary Clinton said she stood with people "defending our values and our constitution", adding: "this is not who we are".
Google was reportedly recalling travelling staff members to the US, saying it was "concerned about the impact of this order and any proposals that could impose restrictions on Googlers and their families".
The International Rescue Committee called President Trump's suspension of the US refugee resettlement program a "harmful and hasty" decision.
The people affected
Some foreign nationals who were allowed to board flights before the order was signed Friday were detained at US airports and told they were no longer welcome.
A Department of Homeland Security official said 109 people who were in transit on planes had been denied entry and 173 had not been allowed to get on their planes overseas.
One Syrian woman with a valid visa was was sent back after arriving in Chicago from Riyadh, and told she could not enter the US to help care for her sick mother.
Two of the first people blocked from entering the United States were Iraqis with links to the US military.
Hameed Khalid Darweesh and Haider Sameer Abdulkhaleq Alshawi were detained by immigration officials after landing at New York's Kennedy airport on Friday night. Both had been released by Saturday night after their lawyers intervened.
Republican congresswoman Nydia Velazquez tweeted a picture of Darweesh talking to reporters after his release.
Six Iraqis and one Yemeni passenger were reportedly barred from flying from Cairo to New York, Cairo Airport sources said.
The passengers, arriving in transit to Cairo airport, were stopped and re-directed to flights headed for their home countries despite holding valid visas, the sources said.
British MP Nadhim Zahawi tweeted that Trump's new immigration order will apply to himself and his wife, meaning they will be banned from travelling to the US.
Zahawi, the Conservative MP for Stratford-on-Avon, and his wife were born in Iraq but are both have British passports.
He told the BBC's Andrew Marr Show that Mr Trump's travel ban had made him feel "discriminated against and demeaned" for the "first time in his life".
Chaos and protests at airports
The order sparked protests at several US airports, including New York's JFK and Chicago's O'Hare.
In San Francisco, hundreds blocked the street outside the arrival area of the international terminal. Several dozen demonstrated at the airport in Portland, Oregon, briefly disrupting rail services.
As protests unfolded, lawyers fled to airports to help people being detained by the authorities.
Some immigration lawyers abandoned dinner parties, grabbed a fax machine and a photocopier, and headed for the airport.
Meanwhile the Governor of New York, Andrew Cuomo, said he had directed authorities to explore all legal options to assist anyone detained at New York airports.
President Trump's executive order issued on Friday but a judge intervened on Sunday and temporarily barred authorities from deporting people from countries subject to Mr Trump's travel ban.
Ann Donnelly said travellers who had been detained had a strong argument that their legal rights had been violated.
The ruling came after lawyers for the American Civil Liberties Union filed a court petition.
The order barred US border agents from removing anyone who arrived in the U.S. with a valid visa from Iraq, Syria, Iran, Sudan, Libya, Somalia and Yemen. It also covered anyone with an approved refugee application.
It was unclear how quickly the judge's order might affect people in detention, or whether it would allow others to resume flying.
Judge ruling 'won't affect implementation of executive order'
Despite the ruling by US District judge Ann Donnelly, the Homeland Security Department said the overall implementation of the President Trump's executive order will not be affected.
The agency said the court order affected a relatively small number of travellers who were inconvenienced by security procedures upon their return.
Stephen Miller, a senior adviser to the White House, said that nothing in the judge's order "in anyway impedes or prevents the implementation of the president's executive order which remains in full, complete and total effect."
Reaction from politicians in UK
Prime Minister Theresa May initially failed to condemn President Trump's ban on refugees entering the United States.
During a press conference in Ankara on Saturday with her Turkish counterpart Binali Yildirim, the PM told reporters: "The United States is responsible for the United States policy on refugees."
Mrs May faced a furious backlash for not taking a harder line, before a Downing Street source said: "We will always find ourselves in agreement on some things and disagreement on other things."
Downing Street later clarified that Theresa May does "not agree" with Donald Trump's refugee ban and will make representations if it hits Britons.
Meanwhile Labour leader Jeremy Corbyn came out strongly against Mr Trump visiting the UK while the travel ban is in place.
He told Peston on Sunday that the president's state visit "might find its way into the long grass", adding "we need to find out exactly what his intentions are".
Mr Corbyn added: "Trump is tearing up international agreements that have lasted, in the case of the Geneva Convention, more than 50 years."
What happens next?
The lawsuit challenging Trump's order was filed on behalf of two Iraqis with ties to US security forces who were detained despite having valid visas.
Hameed Khalid Darweesh, 53, worked for the US Army and for a US contractor in Iraq from 2003 to 2013 as an interpreter and engineer, the lawsuit said.
The second plaintiff, Haider Sameer Abdulkhaleq Alshawi, 33, is the husband of an Iraqi woman who worked for a US contractor in Iraq. She already lives in Houston.
The next hearing in the case was set for 10 February 2017.