The Islamic State group is reporting the death of one of its prominent field commanders during fighting in Libya.

In a eulogy statement posted late Monday on a militant website, the extremist Islamic group said Ahmed al-Ruwaysi, also known as Abu Zakariya al-Tunisi, was killed in recent days amid clashes in the Libyan city of Sirte.

The 166th Battalion, a militia loyal to the un-elected and self-proclaimed Libyan government in Tripoli, is fighting to seize control of Sirte from the ISIS' Libyan affiliate. Libya's elected and internationally recognized parliament has been forced from the capital and meets in the eastern city of Tobruk.

Al-Tunisi, according to his ISIS eulogy, planned and participated in the 2013 assassinations of two prominent left-wing Tunisian politicians: Mohammed Brahmi and Chokri Belaid.