The blast in the town of Ariha in north-western Syria went off as members of the al-Nusra Front gathered at the mosque for iftar, the meal with which Muslims break their fast during the holy month of Ramadan.
Syrian Observatory, which tracks the war, said the explosion in Salem mosque in Ariha, also killed a senior non-Syrian member of the hardline jihadist organisation. Opposition-based social media websites had conflicting casualty figures, with some saying more than 40 people were dead.
No group announced responsibility, but supporters of the al-Nusra Front blamed rival Islamic State militants who have fought the group on several frontlines in Syria. A coalition of rebel groups called Jaish al-Fateh, or “Conquest Army”, in which al-Nusra Front is a major part of its composition, have controlled most of Idlib province since the capture of the provincial capital in March. The region borders Turkey and neighbours President Bashar al-Assad’s heartland in Latakia province on the Mediterranean coast.