AMMAN: The United Nations on Wednesday called for financial aid to assist one million Syrian refugees it says have been forced to flee a conflict that has become an "enormous threat" to the region.

"I appeal to all countries that want to help... I appeal to parliaments, governments to approve extraordinary funds to support the Syrian victims and the countries that receive them," said UN High Commissioner for Refugees Antonio Guterres.

"If that does not happen, with the normal UN aid budgets we will not be able to deliver," he said on a visit to Jordan, which bears the brunt of the refugee crisis.

The UNHCR says the number of Syrian refugees has hit one million two years into a conflict that flared when forces loyal to President Bashar al-Assad began cracking down on democracy protests.

And Guterres said the number of refugees could double or triple by the end of the year unless a solution is found to the conflict.

"This is something host countries and humanitarian agencies will not be able to respond to unless they have a much stronger support from international community," he told the news conference in Amman.

Guterres said Jordan hosts about 450,000 Syrian refugees, calling for aid to help the desert kingdom.

He also called for a political solution to the war in Syria that has killed at least 70,000 people, according to UN figures.

"If one looks at the future, we also need to recognise that this represents an enormous threat to the region, to the peace and security of the region and even further way," said Guterres.

"I appeal to all those that have political responsibility around the world to make everything possible for that political solution to come sooner rather than later.

"If not we might be facing in the near future a catastrophic scenario, this conflict can spill over easily," he warned.