Tunisian authorities have arrested 12 people they suspect are linked to the Sousse beach hotel attack on foreign tourists, and are hunting for two men who trained in a Libyan jihadist camp with the Sousse attacker, an official said.
Thirty-eight foreigners, most British holidaymakers, were killed in Friday's attack before the gunman was shot by police. In March, two gunmen killed 21 people at the Tunis Bardo museum, before they were also shot.
"This is a group who were trained in Libya, and who had the same objective. Two attacked the Bardo and one attacked Sousse," Lazhar Akremi, minister for parliamentary relations, told reporters late on Wednesday. "Police are hunting for two more."
The minister said a total of 12 people had already been arrested since Friday's attack, the worst such massacre in the North African country's modern history.
Islamic State militants, controlling large parts of Iraq and Syria, have claimed responsibility for the Tunisian attack. But authorities say the gunman was not on any police watchlist for jihadist fighters.
Four years after its "Arab Spring" uprising against Zine El-Abidine Ben Ali, Tunisia had emerged as a model for peaceful democratic change. But it is also struggling with the rise of ultra-conservative Islamist groups, some of them violent.
More than 3,000 Tunisians have left to fight for Islamic State and other groups in Iraq, Syria and in Libya, where a conflict between two rival governments has allowed Islamist militants to seek refuge and gain ground.
Tunisian authorities say the Sousse and Bardo museum attackers all received military training late last year in a jihadist camp over the border in lawless southern Libya.