"Over the weekend it became known about the atrocious killing of some 150 people by militants from extremist groups Jabhat al-Nusra and Ansar al-Khilafah during an attack on Khan Assal, a town outside the northern city of Aleppo," the ministry said in a statement on its website.
Both militant groups, which have conducted joint operations in the past, have claimed credit for taking control of Khan Assal on July 22-23 and killing more than 100 soldiers. The Russian ministry expressed deep condolences to the entire Syrian people and strongly condemned the acts by "terrorists and their accomplices" on Syrian soil.
"The barbarous nature of the crime has come as a shock to all Syrians: It has been condemned not only by the country's authorities but also by leading opposition groups," the ministry said.
According to UN data, about 100,000 people have been killed in the Syrian conflict.