The Prime Minister has said that Britain will take thousands more refugees from Syria in response to the worsening humanitarian crisis.

David Cameron made the announcement in Lisbon, where he had been in talks about European reform with his Portuguese counterpart Pedro Passos Coelho.

He said that the extra refugees would come from refugee camps in the region rather than from the thousands who had made their way to Europe, throwing the continent's institutions into crisis. "This provides them with a more direct and safe route to the UK, rather than risking the hazardous journey which has tragically cost so many lives," he said.

Cameron added: "Britain will act with our head and our heart, providing refuge for those in need while working on long term solutions to this crisis." He stressed the need to bring an end to "the conflicts that are driving so many to flee, including the bloodbath that has engulfed Syria".

He did not give a figure for the number of refugees Britain would take, saying that the government would consult with NGOs and announce details next week.

Calls for the UK to take in more refugees have intensified after the publication of a picture of the body of drowned three-year-old Aylan Kurdi, washed up a Turkish beach.

The boy's aunt, Tima Kurdi, told the BBC that his and his brother's death should be "a wake-up call for the whole world".

Cameron has been under increasing pressure to soften the government's tough line against accepting refugees, with influential members of his own back benches critical of its position. A petition to Parliament to accept more refugees got more than three times the necessary 100,000 signatures to make it eligible for debate, while grass-roots movements have seen people offer to make their homes available to people in need.

The move was welcomed by Christian organisations including Christian Aid, whose Head of Middle East, Frances Guy, said: "Countries in the region are hosting an overwhelming number of refugees, and our partners in Syria, Iraq and Lebanon are working to provide succour and support to those fleeing conflict and persecution.

"We commend the Prime Minister's change of heart regarding resettlement, but urge him to be ambitious. The UN refugee agency recommends that the UK resettle at least 10,000 Syrian refugees and we regard this as a minimum. A truly generous response proportionate to the human need would be to accept many more.

"The UK has already contributed generously to help the displaced in the region but that does not exempt us from welcoming those in particular need to these shores.

"Resettlement, however, is only one part of the solution. We call on all Governments to work together for peace in Syria. That should be the priority. Without peace the ongoing displacement in and around Syria will have repercussions for decades to come."

The call for a fair and mandatory EU wide sharing of responsibility for refugees, and extra search and rescue operations, was made today by the Act Alliance EU, a group of European development and humanitarian aid organisations, including Christian Aid, which work closely together with the World Council of Churches.