Nine terrorist suspects have been killed in Tunisia amid security operations ahead of a national march to denounce extremist violence.

Interior Ministry spokesman Ali Aroui said security forces clashed with the suspects in the south west region of Sidi Aich, near the Algerian border.

He said several extremists were wounded in another clash in the north west region of Kef.

The overnight operations around the country come ahead of a march through the capital organised to show solidarity against terrorism, after an attack on a leading museum that left 24 people dead.

Most of those killed in the March 18 attack on the National Bardo Musum were foreign tourists. Two attackers were also killed.

The attack shook the nation's fragile democracy and several foreign officials are expected to attend the march.