BEIRUT (AP) — Kurdish-led fighters in northern Syria are accusing Turkey of being behind an attack there earlier this week.

The U.S-backed Syrian Democratic Forces said that Turkish troops opened heavy machinegun fire on predominantly Kurdish villages. The SDF did not give a word on casualties.

Tuesday's statement came a day after Turkey said Kurdish fighters attacked a Turkish observation post in the northwestern province of Idlib with mortar rounds. Ankara also didn't release any casualty numbers.

Turkey considers the Syrian Kurdish militia a terrorist organization because of its links to Kurdish rebels fighting in Turkey.

The attack in northern Syria occurred in a de-escalation zone that was agreed upon by Russia, Turkey and Iran to reduce the fighting.

The SDF called on those countries to pressure Turkey to "stop its aggression."