AFP/ Amman

British Prime Minister David Cameron visited Syrian refugee camps in Lebanon and Jordan on Monday, pledging increased aim which he said would help stem the migration crisis in Europe.

The surprise visits, which included talks with Lebanon's prime minister and the king of Jordan, came as Cameron appointed a minister to oversee the resettlement of 20,000 Syrian refugees in Britain over the next five years.

As Cameron flew in to Lebanon, his office detailed how an extra 100 million pounds ($153 million, 137 million euros) in British aid for Syrian refugees would be spent.

The premier said in Beirut that Britain was doubling its support for Lebanon's schools to 20 million pounds a year for the next three years to help Syrian refugee children as well as Lebanese.

Boosting aid to regional states hosting refugees was key to tackling the crisis that has seen tens of thousands of asylum-seekers flooding into Europe, Cameron said, reiterating his argument against charges that London was not doing enough.

"Around three percent of the 11 million Syrians forced from their homes have sought asylum in Europe," he said.

"Without British aid, hundreds of thousands more could be risking their lives seeking to get to Europe, so these funds are part of our comprehensive approach to tackle migration from the region."

Cameron travelled on to Jordan for a visit to a Syrian refugee camp and talks with King Abdullah II, Amman's foreign ministry said.

Lebanon and Jordan have complained that their resources have been stretched to breaking point by the influx of refugees from Syria, and UN agencies have repeatedly appealed for aid from donors.

From Britain's additional funding for the refugees announced last week, 40 million pounds will go to UN and other non-governmental groups working with refugees in Jordan, Lebanon and Turkey, Cameron's office said.

Nearly two-thirds of that 40 million pounds will be spent in Lebanon, which is hosting more than 1.1 million refugees in addition to its own population of four million citizens.

Cameron's lightning visit to Lebanon included a stop at an informal refugee settlement outside the town of Terbol in the eastern Bekaa Valley.

"I'm at a refugee camp in Lebanon, hearing some heartbreaking stories," Cameron tweeted as he met refugees who will be resettled in Britain.

The prime minister said he wanted "to see for myself and to hear for myself stories of refugees and what they need".

- 'Huge pressure' on Lebanon -

At a press conference after meeting his Lebanese counterpart Tammam Salam, Cameron acknowledged that the "humanitarian crisis in Syria is putting huge pressure" on Lebanon.

He said he had wanted to witness at first hand "the enormous challenge facing Lebanon as it shoulders the burden of refugees fleeing Syria".

A factsheet issued by his office detailed plans for British support to Lebanon, including food packages and vouchers for refugees, counselling for children and adults, and help for Lebanese municipalities hosting Syrians.

Salam said Lebanon was "grateful for this help which needs to be expanded in view of the deteriorating conditions" for refugees in the country.

"We believe that the refugee problem that has reached the heart of Europe will not stop spreading until a political solution to stop the war in Syria is reached," he stressed.

Cameron's office announced he had named Richard Harrington to a new junior ministerial post in charge of overseeing Syrian refugee resettlement.

In Jordan, Cameron toured Zaatari, a sprawling desert camp in the north of the kingdom that is home to nearly 80,000 Syrian refugees.

The British premier has been under pressure internationally and domestically to address the refugee crisis.

Britain has accepted 216 Syrian refugees over the past year and granted asylum to less than 5,000 since their country's war broke out in 2011 -- far fewer than other European countries like France, Germany and Sweden.

In total, more than four million Syrians have fled abroad from a brutal conflict that has left more than 240,000 people dead.