The attacks targeted the towns of Tarmela, Oreynibe, Najiyeh and Bedama in the province, Mustafa Haj Yusuf, local director of the White Helmets in Idlib, said. 

A total of 662 people, including 149 children and 121 women have been killed and over 4,000 civilians injured in airstrikes since the beginning of this year, according to Idlib Civil Defense Directorate figures.

Located in northern Syria near the Turkish border, Idlib was declared a "de-escalation zone" last year, in which acts of aggression are expressly forbidden.

Syria has only just begun to emerge from a devastating conflict that began in 2011 when the Assad regime cracked down on demonstrators with unexpected ferocity.

UN officials say hundreds of thousands of people have been killed in the conflict.