BEIRUT, March 22 (Reuters) - The U.S.-led coalition air-dropped U.S. and allied Syrian forces near Tabqa in Raqqa province, expanding a campaign by the Syrian Democratic Forces militias against Islamic State, the SDF's Raqqa campaign said on Wednesday.

The operation aims both to capture the strategic Tabqa area across the Euphrates from the SDF's other holdings and to curb Syrian government advances in that direction, the U.S.-backed alliance of militias said in a statement on a social media feed.

(Reporting by Ellen Francis and Tom Perry, editing by Larry King) ((Ellen.Francis@thomsonreuters.com))