At least 19 people were killed, including 17 foreign tourists, when militants attacked Tunisia's Bardo museum in the capital Tunis, Prime Minister Habib Essid said on Wednesday.
A Tunisian citizen and a policeman also died in the attack, Essid said.
Tunisia, whose 2011 uprising against autocrat Zine El-Abidine Ben Ali inspired "Arab Spring" revolts in Egypt, Syria and Libya, has up to now largely avoided the chaos and violence that has plagued those countries.
But Tunisia's armed forces have been fighting Islamist militants who emerged after the uprising.
Several thousand Tunisians have also left the country to fight for militant groups in Syria, Iraq and Libya, and the government is worried about returning jihadis carrying out attacks at home.
