Tunisia has arrested 32 would-be attackers, some of whom were returning from fighting in Syria, who planned "spectacular" attacks, officials have said.
News of the arrests on Saturday came one day after a secular-Islamist coalition cabinet headed by Prime Minister Habib Essid took office.
The new cabinet faces many challenges, including armed groups that emerged after a 2011 uprising.
"Counterterrorism forces foiled plots to carry out spectacular attacks against vital installations, including the interior ministry, security stations and civilian buildings in the capital Tunis," Mohammed Ali Aroui, a spokesman for the interior ministry, told the Reuters news agency.
He said the group included "several terrorists [that have] returned from fighting in Syria".
Aroui said troops killed Tunisian and Algerian fighters in Mount Chaambi, near the Algerian border.
The reports were confirmed by state news agency TAP, which said National Guard and police barracks had been among the intended targets.
Aroui said operations were ongoing, according to TAP.
Since a 2011 uprising in Tunisia toppled the regime of Zine El Abidine Ben Ali, the country has become a major source of fighters travelling to Syria.
With an economy heavily reliant on tourism, Tunisia has been increasing its efforts to stamp out armed groups in the country.
The number of Tunisians fighting in Syria has been estimated at about 3,000. A few hundred have returned to Tunisia and many have been tracked down and arrested.
Aroui did not give details about the identity of this group.