Obama seeks Congress vote before striking Syria

US President Barack Obama said he has decided to take military action against Syria, but will seek authorisation from Congress before he does.

Obama said on Saturday that the US had presented a "powerful case" linking the government of Syrian President Bashar al-Assad to an alleged chemical weapons attack in the Damascus suburbs last week.

"It is a danger to our national security," he said, "that risks making a mockery of the global prohibition on the use of chemical weapons".

In a brief statement delivered at the White House, Obama told reporters that the US military was prepared to launch a "limited" strike, which analysts say will likely entail firing cruise missiles at Syrian army targets.

"I'm confident we can hold the Assad regime accountable for their use of chemical weapons and deter this kind of behaviour and degrade their capacity to carry it out," he said.

Senate Majority Leader Harry Reid said they would hold a vote on authorising the use of limited military force no later than the week of September 9, when lawmakers are scheduled to return from recess.

Reid said the Senate would hold public hearings on the issue next week with senior Obama administration officials, and would hold classified and unclassified briefings for senators throughout the week.

"I believe the use of military force against Syria is both justified and necessary," Reid said in a statement, saying Assad had committed "atrocities" against civilians with a chemical weapons attack.

There were some initial critical reactions from lawmakers, notably Senators John McCain and Lindsey Graham, two longtime Syria hawks who said they would not support a military strike that did not try to topple Assad.

"We cannot in good conscience support isolated military strikes in Syria that are not part of an overall strategy that can change the momentum on the battlefield," they said in a statement.

Earlier on Saturday, Russian President Vladimir Putin demanded that the US provide evidence of the Syrian government's alleged use of chemical weapons to the UN Security Council.

He added that it would be "utter nonsense" for the Syrian government to have used such weapons.

"Syrian government troops are on the offensive and have surrounded the opposition in several regions. In these conditions, to give a trump card to those who are calling for a military intervention is utter nonsense," Putin told reporters in Vladivostok city near the Chinese border.

Syria has denied carrying out the attack, and Prime Minister Wael al-Halqi said on Saturday that Syria's army is ready for potential foreign strikes against it and has its "finger on the trigger".

As tensions rise, Arab foreign ministers will meet in Egyptian capital, Cairo, on Sunday to discuss Syria, Arab League deputy chief Ahmed Ben Helli said.

The meeting had been scheduled for Tuesday, but was advanced "in light of rapid developments in the Syria situation and based on the request of several Arab states," Ben Helli told reporters.

Last Tuesday, the Arab League accused the Syrian regime of carrying out chemical weapons attacks.