Libyan security forces have arrested a suspected leading member of Islamic State, Khalifa al-Barq, in the militant group’s former stronghold of Sirte, an official and residents said on Thursday.

A city official confirmed the arrest but denied that foreign troops had been involved in the operation as claimed by some residents. U.S. troops have several times captured militants in Libya.

Barq was taken from his home in Sirte late on Wednesday, the official said. He gave no more details.

Libyan forces, backed up by U.S. air strikes, expelled Islamic State militants from Sirte in December 2016, a coastal city they had seized in 2015.

Read more: Reuters