At least 16 people have been killed since Wednesday in Syria's eastern province of Deir zur after the start of clashes between pro-Iranian militias and the US-backed Syrian Democratic Forces (SDF), DPA quoted BTA as saying, citing the Syrian Observatory for Human Rights.
The UK-based organization added that seven children were among the dead. At least 35 civilians and seven militants were injured.
Firing and clashes are reported in the countryside, forcing civilians to flee.
Earlier this week, the Syrian Observatory for Human Rights said clashes erupted after tribal fighters loyal to Iran and Syrian President Bashar al-Assad attacked and seized control of checkpoints and military posts of the SDS.
The Syrian Democratic Forces are a close ally of the US in the fight against the “Islamic State” in Syria.
The conflict in Syria began in 2011 with peaceful anti-government demonstrations. Protesters were met with harsh repression by government forces, leading to civil war.
Syrian government forces currently control about two-thirds of the country, while opposition forces mainly control areas in northwest Syria.