The deadly air raids hit the town of Jandairis near the Turkish border, the Britain-based Syrian Observatory for Human Rights war monitor said.

They come six weeks into a Turkey-led assault against the Kurdish People's Protection Units (YPG) militia in the enclave.

Jandairis has come under heavy fire since dawn on Monday as Turkish troops and allied rebels on its edges seek to retake the area from Kurdish fighters, Observatory head Rami Abdel Rahman said.

Since the Turkish offensive started on January 20, Turkish bombardment has killed more than 170 civilians, including 29 children, the Observatory says.

Turkey denies the reports and says it takes the "utmost care" to avoid civilian casualties.

The monitor says 270 pro-Ankara rebels and nearly 310 Kurdish fighters have also lost their lives.

At least 40 Turkish soldiers have also been killed since the start of the assault, according to Ankara.

Since pro-regime fighters were deployed to help the Kurds in Afrin last month, some 58 of these "popular forces" have been killed, it said.

Ankara says the YPG is a "terrorist" extension of the Kurdistan Workers' Party (PKK), which has waged a three-decade insurgency against the Turkish state.

But the YPG has been a key component of a US-backed Kurdish-Arab alliance that has been fighting the Islamic State jihadist group in Syria.

More than 340,000 people have been killed since Syria's war started in 2011. It has since spiralled into a complex conflict involving world powers.