The Islamic State militant group has claimed responsibility for an attack on a museum in the Tunisian capital yesterday which killed 20 foreign tourists, according to an audio recording distributed online.

It praised the two attackers whom the recording said were "knights of the Islamic State" who were armed with machine guns and bombs

Three Tunisians also died in the attack.

Two gunmen opened fire on the Bardo museum, killing tourists from Spain, Poland, Japan, the UK and Colombia, among other nationalities, in the worst attack in more than a decade in the North African country.

The victims included four Italians.

Italy's Costa Cruises said today it had cancelled stops in Tunisia after yesterday's attack. It did not say how long the suspension would last, but a spokeswoman for the company said it could remain in place for the rest of the year.

The militants shot dead by security forces in the attack were identified as Tunisians, Hatem al-Khashnawi and Yassin al-Abidi. Tunisia's Prime Minister, Habib Essid, said the latter had been under surveillance but "not for anything very special".

"We have identified them, it is indeed these two terrorists," the premier told French RTL radio. "Their affiliation is not clear at the moment."

The president's office said the army would be deployed. "After a meeting with the armed forces, the president has decided large cities will be secured by the army," a statement said.