An airstrike killed at least 39 people in a Syrian rebel-held town in the northwest on Saturday when it struck a courthouse and an adjacent prison, the Britain-based Syrian Observatory for Human Rights reported.

The Observatory said that the prison was run by Al-Qaeda's affiliate in Syria, the Nusra Front, and that many of those killed were Nusra fighters and their detainees in the northwestern town of Maaret al-Numan in Idlib province.

The airstrike also wounded a large number of people, many of whom were in critical condition, the Observatory said.

The Local Coordination Committees, another activist group, said the airstrike killed 51. Conflicting figures are common in the aftermath of airstrikes in Syria.

Wire services