Tunisian forces are exchanging fire near the presidential palace with members of deposed President Zine al-Abidine Ben Ali’s guard, reports say.
Witnesses reported heavy gunfire in Carthage, north of the capital Tunis, where the palace is located.
It comes after the ex-head of presidential security, Ali Seriati, was arrested and accused of threatening state security by fomenting violence.
Meanwhile, political leaders are holding talks about a new government.
Interim leader Foued Mebazaa, who until Saturday was the speaker of parliament, has asked Prime Minister Mohammed Ghannouchi to form a government of national unity.
In a national TV address, Mr Ghannouchi said an agreement between the political parties would be announced on Monday. He also pledged “zero tolerance” against anyone threatening the security of the country.
The announcement of Mr Seriati’s arrest on Sunday came after the previous day saw widespread violence across Tunisia, including looting, arson and deadly jail riots.
‘Intensive’ gunfire
The BBC’s Wyre Davies, in Tunis, says that while the Tunisian army does not appear to be interfering in the process of political reform, the motives of some members of the police and security services loyal to the ousted president may be more sinister.
Hours after Mr Seriati’s arrest was announced, heavy gunfire erupted near the presidential palace in the Carthage area.
The army has launched an assault on the palace… where elements of the presidential guard have taken refuge,” AFP news agency quoted a Tunisian military source as saying.
An eyewitness quoted by Reuters news agency said: “There is firing from around the presidential palace, intensive and continuous.”
There was also gunfire near the interior ministry and the headquarters of an opposition party. Two gunmen firing from a roof near the interior ministry were reportedly shot dead by the security forces.
In another development, a group of Westerners – apparently Swedish nationals who were in the country on a wild boar hunting trip – were attacked and badly beaten in Tunis amid reports that foreign nationals were among the presidential guard.
There have also been attacks targeting businesses and buildings connected with the former president and his family.
