An activist group and a Kurdish official say heavy clashes are taking place in northeastern Syria, with Kurdish fighters capturing about a dozen villages from Islamic militants.

Kurdish fighters and members of the Islamic State group have been fighting each other for more than a year in northern Syria.

The latest round of violence between the two sides began Saturday. Members of the Kurdish-led People's Protection Units, or YPK, have captured about 14 villages, according to the Britain-based Syrian Observatory for Human Rights.

Nawaf Khalil, a spokesman for Syria's powerful Kurdish Democratic Union Party, or PYD, told The Associated Press on Monday that YPK forces have captured at least 10 villages in the northeastern province of Hassakeh.