U.S.-backed Syrian force starts new phase of Raqqa assault

RAQQA PROVINCE, Syria, Feb 4 (Reuters) - An alliance of U.S.-backed militias said it had begun a new phase of its campaign against the Islamic State-held city of Raqqa on Saturday and aimed to complete its encirclement.

The Syrian Democratic Forces (SDF) said in a statement the action was being undertaken with "increasing support from the (U.S.-led) international coalition forces through guaranteeing air cover for our forces' advances, or via the help provided by their special teams to our forces on the battle ground".

(Reporting by Rodi Said; Writing by Tom Perry in Beirut; Editing by Alexander Smith)