The dramatic prison swap with Iran has caused controversy, as the deal was dependent on a $6 billion payment, as ITV News' Robert Moore reports
A British-American conservationist is among five prisoners in Iran released as part of a wider deal that sees $6 billion (£4.84 billion) in Iranian assets unfrozen.
The US government has designated all five Americans as being wrongfully detained, and Iran will also receive five of their own citizens from prisons in the states.
The Americans have landed in Doha, Qatar, after flying in a government jet from Tehran. They are expected to make their way from Qatar to Washington DC.
Two relatives of the detainees were also on board, along with the Qatari ambassador to Tehran.
President Joe Biden welcomed the news of the release in a statement, saying “five innocent Americans who were imprisoned in Iran are finally coming home," as he urged Americans against travelling to Iran.
Three of the freed Americans - Siamak Namazi, Emad Shargi, and Morad Tahbaz - were filmed embracing one another after they disembarked the plane in Doha
The release of the Americans brings to an end a years-long nightmare for those who had been detained.
Three of those who are believed to be part of the deal - Emad Shargi, British-American Morad Tahbaz, and Siamak Namazi - had all been imprisoned for more than five years.
The identities of the other two Americans are not publicly known.
Siamak Namazi’s mother, Effie Namazi, and Morad Tahbaz’s wife, Vida Tahbaz – who were previously unable to leave Iran – were also on the flight from Iran to Doha, a senior Biden administration official said.
After stopping in the Qatari capital, they will travel on to the Washington DC area to be reunited with their families, the official said.
Iranian Foreign Ministry spokesman Nasser Kanaani said the exchange would take place on Monday after nearly $6 billion in once-frozen Iranian assets reached Qatar.
"Fortunately Iran’s frozen assets in South Korea were released and God willing today the assets will start to be fully controlled by the government and the nation," Mr Kanaani said.
"On the subject of the prisoner swap, it will happen today and five prisoners, citizens of the Islamic Republic, will be released from the prisons in the US," he added.
"Five imprisoned citizens who were in Iran will be given to the US side."
The cash represents money South Korea owed Iran - but had not yet paid - for oil purchased before the US imposed sanctions on such transactions in 2019.
Their release represents a significant diplomatic breakthrough after years of complicated indirect negotiations between Washington and Tehran.
The United States and Iran do not have formal diplomatic ties, and relations further plummeted under the Trump administration, when the US withdrew from the Iran nuclear deal and pursued a “maximum pressure” approach to Tehran.
In the years since, efforts to constrain Iran’s growing nuclear program have been unsuccessful.
Meanwhile, Tehran has continued to perpetrate human rights abuses against its own people.
Last year’s death of 22-year-old Mahsa Amini in the custody of Iran’s so-called morality police prompted nationwide protests which were brutally suppressed.
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