Turkish warplanes targeted pro-Syrian regime forces in the northwestern Syria's Afrin on Saturday.
The Turkish strikes killed at least 36, according to the Syrian Observatory for Human Rights.
The Observatory said this hit was the third to take place in the past 48 hours.
The Turkish warplanes had struck pro-regime forces that entered Afrin last week in support of the Kurdish YPG militia, according to Reuters.
Turkey launched its air and ground offensive on Afrin last month, seeking to drive out the YPG, which it deems a security threat along its border.
Meanwhile, Syrian regime airstrikes and bombardment have killed hundreds of people over 12 days in eastern Ghouta.
A top UN human rights official said Syrian regime airstrikes on the besieged Syrian enclave of eastern Ghouta probably constitute war crimes and must be prosecuted.
Reuters reported Zeid Raad Hussein, United Nations High Commissioner for Human Rights, saying "the perpetrators of such crimes in Syria should know they were being identified and that dossiers were being built for future prosecutions."
The Britain-based Syrian Observatory for Human Rights and the Syrian Civil Defense said six civilians were killed Saturday in government bombings in eastern Ghouta, AP reported.
The UN Security Council called recently for a 30-day ceasefire in eastern Ghouta, where 400,000 people live.
