Tunisia will shut down about 80 mosques accused of inciting violence, Prime Minister Habib Essid has said, after a beach attack that left 39 people dead.
The mosques, which operate outside state control, are spreading "venom" and will close within a week, he said.
On Friday a gunman opened fire on tourists in the resort town of Sousse.
Tunisians, Britons, Germans, Belgians, French and at least one Irish citizen were among those killed in the attack, claimed by Islamic State (IS).
The gunman was shot dead by police. Officials say he was a student not previously known to authorities.
This was the second major attack on tourists in Tunisia since March, when militants killed 22 people, mainly foreigners, at a museum in the capital.
Speaking at a news conference in Tunis, Mr Essid said: "Some mosques continue to spread their propaganda and their venom to promote terrorism."
He said they would be closed by the interior ministry.
Mr Essid also vowed to act against parties and groups "acting outside the constitution" - such action could range from a warning to closure.
Referring to Friday's attack, Mr Essid said most victims were British, without providing details.
Earlier, UK Foreign Secretary Philip Hammond said at least five Britons were confirmed dead, adding: "We must expect more reports of fatalities".
Security officials said one attacker, who had posed as a swimmer but was carrying a rifle under a parasol, started shooting on the beach before entering the Hotel Riu Imperial Marhaba, continuing to shoot.
One British holidaymaker in Sousse, Steve Johnson, told the BBC: "We were just lying on the beach as usual and... we heard what we thought at first was fireworks.
"But it was soon pretty obvious... that it was firearms that were being discharged and people screaming and starting to run."
IS said it was behind Friday's attack, identifying the gunman as Abu Yahya al-Qayrawani. Social media accounts close to the group showed pictures of him.
IS had urged followers to step up assaults during the holy Muslim month of Ramadan.
