A U.S. military official says fighting against the Islamic State group in its last enclave in eastern Syria "is going very well."

Col. Sean Ryan, a spokesman for the U.S.-led Coalition, comments on Saturday came a day after the U.S.-backed Syrian Democratic Forces captured the town of Hajin, the largest urban area controlled by IS in the enclave.

Ryan said IS still poses a threat and its fighters are regrouping, planting improvised explosives devices to slow the progress of SDF offensives.

He added that the "end days" of IS in the enclave they hold near Iraq's border are getting closer, however, "they still have the capability for coordinated attacks, and the fight is not over."

SDF has been trying to take the enclave for more than three months.