Coalition forces conducted an air strike Tuesday in Syria targeting a "senior leader" from the Islamic State group, a US defense official said, amid reports the jihadists' spokesman Abu Mohamed al-Adnani had been killed. 

"Coalition forces conducted an air strike in Al-Bab, Syria, targeting an (IS) senior leader," the official said, speaking on condition of anonymity. "We are still assessing the results of the operation at this time."

Al-Bab is in Aleppo province, where the Islamic State group said Adnani was when he was killed.