A spokesman for Tunisia's Interior Ministry said on Sunday that security forces had killed the alleged extremists in the south of the country late on Saturday.

"Our forces killed nine terrorists in a large operation in Sidi Aich in Gafsa. They also captured arms and explosives," spokesman Mohamed Ali Aroui told the Reuters news agency.

The news of the operation came just hours after it emerged that a fourth French national had died of wounds sustained in an attack on tourists at the National Bardo Museum in Tunis on March 18, raising the death toll to 22. Tourists from Italy, Japan, Spain, Colombia, Australia, Britain, Belgium, Poland and Russia were among the other victims.

The "Islamic State," which has seized large swathes of territory in Syria and northern Iraq over the past year, has claimed responsibility for the attack, in which two of the gunmen were shot dead by security forces. Tunisian authorities though, have blamed the local Islamist group Okba Ibn Nafaa for the attack.

Anti-extremism march

Meanwhile, thousands of Tunisians and several foreign dignitaries, including French President Francois Hollande and Italian Prime Minister Matteo Renzi were expected to join a rally against extremism in Tunis later in the day. The march through the capital is to end at the Bardo Museum, where a stone tablet dedicated to the victims of the attack is to be officially unveiled.

Tunisia has seen in increase in Islamist attacks since longtime strongman Zine El Abidine Ben Ali was toppled in a popular uprising in 2011. However, the country that was the cradle of the "Arab Spring" revolutions that swept through the region at the time has also widely been regarded as a model of successful transition to democracy.

pfd/sms (Reuters, AFP)