Abu Mohammad al-Adnani
Abu Mohammad al-Adnani Screenshot

The United States carried out an air strike on Tuesday targeting one of Islamic State's (ISIS) longest serving leaders, Abu Muhammad al-Adnani, a U.S. defense official has confirmed, according to Reuters.

The U.S. official said the strike targeted a vehicle in the town of al-Bab in Syria but declined to say whether Adnani was indeed killed.

ISIS's news agency earlier reported that al-Adnani had been killed, saying he was “martyred”, but failing to provide details of the circumstances of his demise.

"Shaykh Abu Muhammad al-Adnani, the spokesman of the Islamic State, was martyred while surveying the operations to repel the military campaigns against Aleppo," said the news agency, Amaq.

An American official subsequently confirmed that forces from the U.S.-led international coalition conducted an air strike in Syria targeting a "senior leader" from ISIS, but did not name him nor say whether the strike was successful.

Al-Adnani, who served as a spokesperson for ISIS, was believed to have been the organization’s second highest ranking leader, after founder Abu Bakr al-Baghdadi.

He was heard from as recently as last May, calling for attacks on the U.S. during the holy month of Ramadan.