Clashes on Sunday between Turkish-backed rebel factions vying for influence in the northern Syrian town of Afrin left 25 fighters dead, a war monitor said.
Turkish troops and allied rebel groups seized the Afrin region from Kurdish forces in March after a two-month air and ground offensive.
The Britain-based Syrian Observatory for Human Rights said fighting in several districts erupted on Saturday.
Turkish troops stationed in the town imposed a curfew on civilians from Saturday evening in a bid to avoid bloodshed, the Observatory said.
The clashes pitched the majority of the pro-Ankara rebels against a group of some 200 fighters who were accused of “disobeying” Turkish forces and “committing abuses”, the monitor said.
The main alliance of Turkish-backed rebels in Afrin wrote on Twitter that current operations were aimed at “pursuing outlaw gangs”.
Since Turkish troops and pro-Ankara Arab rebels captured the town from the Kurdish People’s Protection Units (YPG), the United Nations and human rights groups, including Amnesty International, have documented widespread abuses.
Half of the enclave’s 320,000 residents fled, according to a report by the UN Commission of Inquiry, and most are unable to return.