The first group of unaccompanied children without family ties to the UK has arrived in Britain from the migrant camp in Calais.
They came under the “Dubs amendment” rules which allow particularly vulnerable children – such as girls and those under 13 – refuge in the UK.
They were among 70 boys and girls to be taken to London from the “Jungle” camp.
French police have clashed with migrants at the site, which is scheduled to be closed on Monday.
About 10,000 leaflets are due to be distributed by the French authorities, telling people to report from Sunday morning to a hanger, where they will be taken by bus to other parts of France and given the opportunity to claim asylum.
But there is concern among charities that some migrants will refuse to go to reception centres elsewhere in France, because they still want to get to Britain.
As many as 10,000 people, mainly from Africa and the Middle East, are estimated to live in the camp and there have been scenes of violence as some attempt to board lorries bound for the UK, clashing with drivers and police in the process.
The Dubs amendment was passed following the efforts of Labour peer Lord Dubs who successfully campaigned for an amendment to the Immigration Bill in April.
It allows for unaccompanied child refugees to be brought to the UK where they do not have family links but are considered to be particularly at risk.
All of the children brought to Britain earlier this week entered under the so-called Dublin regulation, which meant they had to provide evidence they had a relative in the UK who could be responsible for their care for their claim for asylum to be heard.
But their arrival prompted controversy in several criticisms from Monmouth MP David Davies, with suggestions that some of them looked older than 18 years.
He said young migrants should have their teeth tested to verify their ages. The call was rejected by the government which pointed out such examinations have been described as “inaccurate, inappropriate and unethical” by dental experts.
Scaffolding and sheets were erected around the entrance to the Home Office building in Croydon, south London, where Saturday’s arrivals were taken, to shield them from the media.
Sources said that 50 to 70 young refugees are expected to be taken to a hostel in north Devon on either Sunday evening or Monday morning.
Bishop of Croydon Jonathan Clark a spokesman for the campaign group Safe Passage UK, said the new arrivals were “not just children seeking to reunite with their families, but also the most vulnerable who are at last being transferred to Britain“.
He added: “With demolitions due to begin on Monday we remain extremely concerned that children will go missing and urge government to redouble its efforts to transfer all the eligible children in Calais, and ensure the rest are adequately protected.”
Speaking at a separate rally in central London calling on the UK to take a larger role in ending attacks on civilians in Syria, the actress Carey Mulligan said the arrival of the children from Calais this week showed the government had taken a “strong stance” on the issue.
Meanwhile, the Sunday Telegraph reported that the Home Office rejects an offer in August of expert help from social workers to establish the ages of asylum seekers in Calais who wanted to enter the UK.
According to the paper, officials only started asking for specialist help on Friday after questions were raised by some MPs about their ages.
David Simmonds, chairman of the Local Government Association’s asylum, refugee and migration taskforce said, “We made the offer in August and the Home Office didn’t take it up at the time. They only started asking for social workers with age assessment experience on Friday.”
Home Office source said the support had not been needed when it was first offered.