BEIRUT (Reuters) - A field commander for the U.S.-backed Syrian Democratic Forces (SDF) in Raqqa said the alliance was carrying out clearing operations against Islamic State and expected to control the city by the end of Monday.  Ilham Ahmed, a senior Kurdish leader who co-chairs the SDF s political wing, said she expected the end of the Raqqa offensive to be announced  within hours or days , but a U.S.-led coalition spokesman said he could not put a timeline on it. (This version of the story clarifies title of leader affiliated with SDF) 