Australia will increase its aid contribution to Syria and Iraq by $25 million, Foreign Minister Julie Bishop says, bringing the total amount of humanitarian assistance since 2011 to $258 million.

World leaders and senior diplomats gathered in London overnight, promising to provide more than $13.5 billion to Syria and surrounding countries.

Australia donated less than some charities had hoped, but Ms Bishop also flagged a new, un-costed multi-year assistance package to help Jordan and Lebanon deal with the influx of Syrian refugees.

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“It is vital that Syrian refugees have the opportunity to contribute to their host countries and the communities within and to develop the skills necessary to help rebuild their country after the conflict is over,” she said.

“Without such opportunities we risk a lost generation.”

Ms Bishop said both the Government and the Opposition felt compelled to help those suffering through what she called the world’s worst humanitarian crisis.

“While today we’re discussing the humanitarian needs of this crisis we mustn’t lose sight of the fact that the only solution is to end the conflict,” she said.

“The Syrian regime and opposition must negotiate seriously to achieve a ceasefire as a prelude to a lasting peace.”

Saudi Arabia back plan for ground troops in Syria

Germany and the United Kingdom pledged to provide more than $2 billion each, with UN Secretary General Ban Ki-Moon saying it was overall an amazing effort.

“Never has the international community raised so much money on a single day for a single crisis,” he said.

“Today’s pledges will enable humanitarian workers to continue reaching millions of people with lifesaving aid.”

The meeting was overshadowed by the suspension of peace talks and intense fighting on the ground, and a new discussion of ground troops.

Saudi Arabia is ready to join any ground operation the US-led coalition against Islamic State in Syria might decide on, a general from the kingdom said.

“If there is any willingness in the coalition to go in the ground operation, we will contribute positively in that,” Brigadier General Ahmed al-Assiri told AFP.

Meanwhile, underlining the desperate situation on the ground in Syria, Turkish Prime Minister Ahmet Davutoglu told the meeting that up to 70,000 Syrians were on the move towards his country to escape aerial bombardments on the city of Aleppo.