Kerry urges Assad to end killing

US Secretary of State John Kerry has urged Syria's embattled President Bashar al-Assad to end the killing in his country.

Citing a phone conversation with Saudi Arabia's foreign minister, Kerry said that according to an estimate by the Saudis, "perhaps as many as 90,000 people who have been killed in Syria", Xinhua reported.

This number is much higher than the UN estimate of a death toll of nearly 70,000.

The "vast numbers of refugees" creates enormous dislocation and burdens on the countries that are prepared to receive them, Kerry said.

"President Assad has the ability to be able to make the difference here by deciding to engage in a legitimate diplomatic process."

"He must end this killing."

Kerry also called on the international community to respond to the UN's appeal for more funds and more humanitarian assistance to help the violence-affected Syrians both inside and outside the country.

The UN estimates that more than 750,000 people have fled Syria to seek refuge, while about 2.5 million people are displaced within the country.