WASHINGTON (AFP) - The United States will engage allies on how serious Syria is about surrendering its chemical weapons, but stands by its drive to muster support for possible military action, the White House said on Tuesday.

Spokesman Jay Carney spoke on MSNBC hours after Syria confirmed it had embraced a Russian proposal to put its chemical weapons - which the US says it had never even acknowledged having - under international supervision with an eye to their eventual destruction.

"We will engage and have been engaged in intense conversations with our friends and allies internationally about this process, about moving forward and testing the seriousness of the Syrians when it comes to the potential for them giving up their chemical weapons stockpile," Mr Carney said.

He spoke a day after President Barack Obama, who had asked Congress for approval to attack Syria in retaliation for what the White House says was a devastating chemical weapons attack August 21 against civilians, gave a cautious welcome to the weapons surrender idea.

Mr Obama is scheduled to address the American people on prime time TV on Tuesday night.

The original goal had been to garner support for military action against Syria amid war weariness among every day people and lawmakers after decades of involvement in Iraq and Afghanistan.

Even though Syria now says it is willing to surrender its chemical weapons, Mr Obama will still make the case for possible military action, Mr Carney said.

"He'll be building support for calling on Congress as well as the American people to understand and support the action that he's proposed," Mr Carney said.