Suspected Russian air strikes on a camp in northwestern Syria run by Turkish-backed militia fighters have reportedly killed at least 50 people and wounded scores of others.
Youssef Hammud, a spokesman for Syrian opposition groups, blamed Russia for the October 26 air strikes in the mainly rebel-held province of Idlib that targeted a military training camp for the Islamist group Faylaq Al-Sham.
The British-based Syrian Observatory for Human Rights put the number of dead at 78, with nearly 90 wounded.
The group said it suspected that the air strike in the Harem region northwest of Idlib City was carried out by Russia, Syrian President Bashar al-Assad’s main ally in the country's nine-year-long civil war.
There was no immediate comment from Moscow or Ankara, which although they support opposite sides in the conflict, have worked together to maintain a cease-fire in Idlib Province.
The strike was said to be the deadliest in Idlib since the truce came into effect in March, bringing to a halt a Syrian government offensive on the region.
After the cease-fire was announced, Turkey said it reserved the right to "retaliate with all its strength" against any attack by forces allied to Assad.