UK aid to Syria is to increase by at least £1.2 billion, more than doubling to £2.3bn the country’s current contribution to the world’s largest humanitarian crisis.

David Cameron's announcement comes as heads of government and other senior officials from 70 countries gather in London today for a special conference to seek ways of helping the war-ravaged country and the 4.6 million registered Syrian refugees.

It also follows the suspension of UN-sponsored peace talks aimed at ending Syria's five-year civil war; officials said there had been a lack of progress in the first week. The talks are due to resume in three weeks’ time.

Last year, a similar aid conference only raised $3.5bn, half of the United Nations target; this year’s target is also $7bn. The UK’s increased contribution represents a quarter of this amount and will be seen as an attempt by Britain to encourage other countries to contribute more.

Announcing the additional UK taxpayer contribution, the Prime Minister said: “With hundreds of thousands of people risking their lives crossing the Aegean or the Balkans, now is the time to take a new approach to the humanitarian disaster in Syria.

“Today’s pledge of more than £2.3bn in UK aid sets the standard for the international community; more money is needed to tackle this crisis and it is needed now,” declared Mr Cameron.

But he stressed the Supporting Syria and the Region conference Britain was co-hosting today alongside Germany, Norway, Kuwait and the UN was more than just about money.

“Our new approach of using fundraising to build stability, create jobs and provide education can have a transformational effect in the region and create a future model for humanitarian relief.

“And,” added the PM, “we can provide the sense of hope needed to stop people thinking they have no option but to risk their lives on a dangerous journey to Europe.”

Yesterday at a Syria civil society conference in London, Justine Greening, the International Development Secretary, said the world faced an "historic opportunity" to draw up a new deal to help Syrian refugees fleeing their country's brutal civil war.

Andy Baker, for Oxfam, described it as "the defining crisis of our time" but said the international community had so far failed in its response.

He claimed the conflict was a "proxy war" and called on the West to take in more refugees and to increase aid.

The new UK money will be invested over the next four years and will help fund education, jobs and humanitarian protection in Syria, Jordan, Lebanon and Turkey.