LONDON — Britain says it will put forward a resolution Wednesday to the U.N. Security Council condemning the Syrian government for the alleged chemical attack that has killed hundreds of civilians.

A statement from Prime Minister David Cameron's office said Britain would seek a measure "authorizing necessary measures to protect civilians" in Syria. Military force is one of the options that can be authorized under Chapter 7 of the U.N. charter.

The decision came as momentum appeared to build for Western military action against Syria, with the U.S. and France saying they are in position for a military strike.

The prospect of a U.S.-led intervention into Syria's civil war stems from the West's assertion — still not endorsed by U.N. inspectors — that President Bashar al-Assad's government was responsible for an alleged chemical attack on civilians outside Damascus on Aug. 21, which Assad denies.

Doctors Without Borders says that attack killed 355 people.