Russian Defense Ministry on Thursday denied the involvement of the alleged airstrikes on a school in the Syrian city of Idlib, saying the evidence spreading among some media was "fabricated."

"The video of an alleged airstrike that appeared in a various foreign media was made of ten clips put together, and shot with a different resolution at different time," the ministry's spokesman Maj. Gen. Igor Konashenkov said in a statement.

The Britain-based Syrian Observatory for Human Rights (SOHR) said on Wednesday that an air raid allegedly carried out by Russian warplanes targeted civilian areas in Idlib, including a school compound, killing at least 26 civilians, most of them children and teachers.

The Syrian state TV quoted a military source as saying that a number of militants had been killed after the strikes on the targets in Idlib, but it neither mentioned any school, nor civilian casualties.

"This is a tragedy. It is an outrage. And if deliberate, it is a war crime," executive director of the United Nations Children's Fund Anthony Lake said Wednesday, calling the strike "the deadliest attack on a school" in the five-and-a-half-year-long crisis in the war-raged Middle East country.