Arab League foreign ministers have urged the international community and the United Nations to take "deterrent" action against the Syrian regime over its alleged use of chemical weapons.

"The United Nations and the international community are called upon to assume their responsibilities in line with the UN Charter and international law by taking the necessary deterrent measures", the ministers said in a statement on Sunday following a meeting in Cairo.

It said that the Syrian regime of President Bashar al-Assad was "responsible" for the August 21 attack.

The foreign ministers also said those responsible for the attack should face trial, as other "war criminals" have done.

Earlier, Saudi Arabia and the Syrian opposition pleaded with League members to back a US military strike on the regime.

Saudi Foreign Minister Saud al-Faisal told the meeting that "opposition to international action only encourages the regime to pursue its crimes".

"It is time to ask the international community to assume its responsibilities and to take deterrent measures" against the Syrian regime," al-Faisal said.

The head of the Syrian National Coalition, Ahmed al-Jarba, told the meeting that the "war machine" of Assad must be stopped.

"I am here before you today to appeal to your brotherly and humanitarian sentiments and ask you to back the international operation against the destructive war machine," he said.

The umbrella coalition of opposition groups has been recognised by the League as Syria's representative following the barring of Assad's regime in 2011.

However, some influential members of the League, including Egypt, Iraq, Lebanon, Tunisia and Algeria, have expressed opposition to foreign military intervention.

Egypt's foreign minister on Sunday said that his nation objected to "any aggression in Syria".

The US says it has evidence that the Assad regime launched the August 21 chemical attack on the outskirts of Damascus, which it says killed more than 1,400 people. Other estimates by aid groups are more conservative, putting the toll in the hundreds.

The Syria regime denies it was behind the attacks. The Arab League last week condemned the attack, but said any action must be mandated by the United Nations.