U.S.-backed Syrian fighters say they are battling the Islamic State group in eastern Syria 10 days after declaring victory over the extremists.

Mustafa Bali, a spokesman for the Kurdish-led Syrian Democratic Forces, said Tuesday that they are rooting out groups of militants who were hiding in caves in and near the village of Baghouz.

The Britain-based Syrian Observatory for Human Rights says the U.S.-led coalition is still conducting airstrikes against IS. It added that senior IS commanders and prisoners held by the extremists are believed to be in the caves on the east bank of the Euphrates River.

The SDF declared military victory over IS on March 23 after liberating what it said was the last pocket of territory held by the militants.