- Video report by ITV News International Affairs Editor Rageh Omaar
Vigils have been held across the UK and a minute's silence was observed in the House of Commons for the 49 victims of the two mass shootings at mosques in New Zealand.
Police patrols around mosques in the UK have also been "stepped up" in a bid to offer "reassurance" in the wake of the terror attack, the country's counter terror police chief has said.
As well as the 49 deaths, 48 others were injured in two terror attacks at Masjid Al Noor in central Christchurch and Linwood Masjid in a suburb of the city.
Police have arrested three people in connection with the terror attack, charging a 28-year-old man with murder.
A vigil for the victims of the attack was held outside New Zealand's embassy in the UK from 12pm on Friday, promoting the idea that "love will win and terror will lose".
The event was organised by Turn To Love, a global anti-terrorism campaign set up to honour the victims of attacks, which also organised vigils in the wake of the London Bridge, Manchester, Westminster, and Finsbury Park attacks in the UK.
The group assembled with placards and posters, holding up signs which read "They will not divide us" and "Turn to love for New Zealand".
One minute's silence was also held for the victims.
Labour leader Jeremy Corbyn attended the event, telling the crowd: "We will not allow these people to divide us, we will stand in solidarity with all those who suffered egregiously in New Zealand.
"We stand together for a world where we respect each other, where we recognise the strength that comes from our diversity.
"And recognise an attack on any one community or any one place of worship, whatever the faith, is actually an attack on all of us."
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Mustafa Field OBE, director of Faith Forums for London, said: "Jeremy sent a really powerful message of solidarity with the Muslim community that the perpetrators will not divide us.
"We will stand firmly together as Brits with the rest of world."
Mr Corbyn also laid a wreath for the victims and met New Zealand's ambassador to the UK, Sir Jerry Mateparae, to discuss the attacks in Christchurch, to which he said his reaction was one of "shock and horror".
A separate vigil has been organised by Muslim Welfare House which runs a network of community centres serving Muslims in England and Wales, Finsbury Park Mosque, Citizens UK and Islington Stand up to Racism, and will take place outside Finsbury Park tube station in London at 6.30pm on Friday.
Also on Friday, the Bishop of London and other faith leaders will be meeting at the East London Mosque in a show of solidarity.
While in Cardiff, a vigil organised by the Muslim Council of Wales will be held on Friday evening in solidarity with the victims of the attack.
It will begin at 6pm at The Temple of Peace.
The vigils come as patrols around mosques in the UK are being stepped up to offer "reassurance" to communities.
Neil Basu, the UK's National Policing lead for counter terrorism, said officers would also be "increasing engagement with communities of all faith, giving advice on how people and places can protect themselves...
"We are monitoring events in New Zealand closely and send our condolences to all those affected.
"We stand together with all our communities and partners here in the UK and overseas, and will continue to work with them to counter the threat no matter where it comes from."
Messages of condolences have also been sent from the UK, with the Queen telling the people of New Zealand that they are in her prayers.
New Zealand is part of the Commonwealth, meaning the Queen is their monarch and head of state.
In her message, the Queen said she was "deeply saddened by the appalling events in Christchurch today.
"Prince Philip and I send our condolences to the families and friends of those who have lost their lives.
"I also pay tribute to the emergency services and volunteers who are providing support to those who have been injured.
"At this tragic time, my thoughts and prayers are with all New Zealanders."
The Prince of Wales added the attacks were an "appalling atrocity" and "an assault on all of us who cherish religious freedom, tolerance, compassion and community".
And in a joint message, the Duke and Duchess of Cambridge and the Duke and Duchess of Sussex said: "We have all been fortunate to spend time in Christchurch and have felt the warm, open-hearted and generous spirit that is core to its remarkable people.
"No person should ever have to fear attending a sacred place of worship."
The Muslim Council of Britain condemned the "horrific, cowardly and Islamophobic terrorist attacks" and sent their "condolences to the families affected".
Harun Khan, Secretary General of the Muslim Council of Britain added: "As the rest of us prepare to undertake our own Friday prayers today, we do so with the anxiety as to whether our mosques and communities are safe in the face of unabated Islamophobia and hostility against Muslims.
"I call on our Government to redouble its efforts to ensure mosques are protected, and call on fellow Muslims to resist the temptation to roll up the banners in fear, as this attack was designed to do.”
While Anas Altikriti, President of the Muslim Association of Britain, said: "Our prayers and thoughts are with the victims and their families during this incredibly difficult time, and to the entire Muslim community in New Zealand.
Prime Minister Theresa May also sent her "deepest condolences" to New Zealand following the "horrifying terrorist attack", adding "my thoughts are with all of those affected by this sickening act of violence".
"We look forward to the authorities in New Zealand securing the safety of all its citizens, hope that the perpetrators will be captured and any further threat to innocent lives be brought to a swift end."
Home Secretary Sajid Javid added he was "heartbroken" by the attack on "peaceful worshippers", adding that the UK stands "with New Zealand and Muslims across the world against all forms of racism and anti-Muslim hatred.
"We will not let extremists divide us."
While Foreign Secretary Jeremy Hunt said the UK "stands with" New Zealand in "deepest sympathy".
Labour leader Jeremy Corbyn tweeted: "We stand in solidarity with the Muslim community in Christchurch and around the world.
"We must defeat the bigotry which fuels such hatred and violence."