Tunisian Prime Minister Habib Essid has confirmed the killing of Algerian Khaled Chaib (Lokman Abu Sakhr), leader of the Okba Ibn Nafaa Brigade.
He was killed near Gafsa on 28 March after clashes with security forces. Eight other alleged terrorists were killed in the operation.
The Tunisian government is blaming the attack on the Bardo Museum, on 18 March, on the Okba Ibn Nafaa Brigades. The attack killed 22, mainly foreign tourists.
The group has been fighting a guerrilla war with security forces around Chaambi Mountain on the Algerian border since 2013.
Dozens of suspected terrorists have been arrested in Tunisia since the attack in a crackdown against extremism, and several senior members of the security forces sacked.
The news comes as President Hollande of France, President Mahmoud Abbas of Palestine, President Bronislaw Komorowski of Poland, Italian Prime Minister Matteo Renzi and President Ali Bongo Odimba of Gabon join thousands of Tunisians to attend a rally against terrorism in Tunis.
The Bardo Museum reopened on March 27.