British celebrities including actress Keira Knightley, rock band Coldplay and former England striker Gary Lineker, urged the UK government on Tuesday to save a programme to take in vulnerable child migrants from Europe.

Under a change to immigration law known as the Dubs amendment, which was passed by parliament last year, Britain agreed to accept "vulnerable" child migrants who had arrived in the European Union before March 20, 2016.

But last week, the government announced plans to scrap the scheme it said encouraged human trafficking.

The decision sparked criticism from aid agencies, opposition lawmakers and the Archbishop of Canterbury.

In an open letter to British Prime Minister Theresa May more than 200 actors, musicians, authors and broadcasters said the government's decision was shameful and embarrassing.

"The country we know and love is bigger than this," they wrote in a letter backed by charities Citizens UK and Help Refugees.

"The government must agree to extend the programme and re-consult with councils immediately."

The stars said it was "completely unacceptable" to close the door to children after just 350 have been accepted.

Others who signed the letter included actors Emma Thompson, Ralph Fiennes, Benedict Cumberbatch, Jude Law, musician Lily Allen, artist Anish Kapoor and writer Sarah Waters.

"The outpouring of support for the continuation of the Dubs scheme by these well-known figures and the public demonstrates that its closure is at odds with the British values that make this country great," said Help Refugees co-founder Josie Naughton.

"We ask that the government finds a way to do more to protect these vulnerable children fleeing war and conflict just as we did before the Second World War'," Naughton said in a statement.

Conflicts and poverty in the Middle East and Africa have forced more than 1 million people to head to Europe, fuelling the region's largest migrant crisis since World War Two.

Around 30,000 unaccompanied children arrived in Greece and Italy alone in 2016, according to the United Nations children agency UNICEF.