The Home Office is to write to councils urging them to take migrant children who have arrived in the UK without any parents or guardians.
A voluntary scheme is now going to be compulsory, meaning youngsters being looked after by authorities on England’s south coast will be moved to other parts of the country.
The Home Office will send more than 200 councils a letter giving them two weeks to present reasons why they should not accept them.
They are expected to be told about the change later on Tuesday.
It comes after the Home Secretary defended her efforts to tackle the migrant crisis.
Enver Solomon, chief executive of the Refugee Council, said: “Children who arrive in the UK on their own seeking safety are highly vulnerable. They must receive local authority care immediately, a responsibility that must be shared equitably by all local authorities in the UK.
“This important decision should reduce the unacceptable delays in vulnerable children, who have often experienced great trauma, getting the vital care they need and is a very welcome move.”
Priti Patel told MPs in the House of Commons on Monday that councils around the UK needed to “play their part” in offering accommodation to asylum seekers.
Councillor James Jamieson, chairman of the Local Government Association, said the majority of councils had stepped forward voluntarily to offer help and that authorities will want to work “closely with government to ensure the rights and needs of children are at the heart of these new arrangements”.
He added: “These need to enable local partners to give children the help they need, including mental and physical health support and appropriate education.
“Councils continue to face challenges in finding appropriate homes, with ongoing issues around centrally-led age assessment and delays in decision-making adding uncertainty for both councils and young people.
“These new arrangements must continue to swiftly take into account existing pressures in local areas, with greater join up across government to improve engagement with councils on all the programmes that support new arrivals to start new lives in the UK.”
Ms Patel told MPs “there is no silver bullet” to tackling the migrant crisis, adding: “The only solution is wholescale reform of our asylum system.”
Ms Patel also insisted she was the only Home Secretary to have considered a reform of the entire immigration system and also denied she had ever suggested using wave machines as a way of turning back migrants at sea, despite media reports at the time suggesting this was one of several ideas being looked into by ministers and officials.
She added: “That is something that I have never, ever suggested or recommended.”
Figures show the number of people who have made the dangerous journey across the English Channel in small boats so far this year is now three times the total for the whole of 2020.
At least 886 people succeeded in reaching the UK on Saturday, bringing the total for the year to more than 25,700, while around 8,500 people crossed the Dover Strait last year.
The figures are based on Home Office data obtained and analysed by the PA news agency.
A Home Office spokeswoman said: “The Government is working to ensure the needs of newly arriving unaccompanied asylum-seeking children are met.
“We are grateful for the continued support of local authorities to provide vital care to vulnerable children and we continue to keep the National Transfer Scheme under review to ensure a fair and equitable distribution of responsibility across the UK.”