Tunis, Jan 16 (Agencies): Tunisia's new acting President pledged an open political system on Saturday following the abrupt end of former strongman Zine El Abidine Ben Ali's 23-year rule as the Arab State veered towards chaos.

Soldiers and tanks were deployed around the capital Tunis after extensive looting of shops and homes and vandals set fire to the main railway station.

The crackle of gunfire echoed in the largely deserted streets of the city centre, which was sealed off by security forces to prevent protests.

Tunisia has been under a state of emergency since Friday, which bans any public gatherings and imposes a strict dusk-to-dawn curfew.

After being formally sworn into office to take over from Ben Ali, 78-year-old speaker of parliament Foued Mebazaa said that all Tunisians "without exception" would now be able to take part in national politics.

"A unity government is necessary in the greater national interest," Mebazaa added, as the Constitutional Council declared that a presidential election should be held in two months' time.

The exiled head of the main Tunisian Islamist party, which was banned by Ben Ali, said he now planned to return to his homeland.

"The Tunisian intifada has succeeded in collapsing the dictatorship," said Rached Ghannouchi, leader of the Ennahdha party, speaking from London.

Meanwhile there were chaotic scenes in and around Tunis on Saturday.

In Monastir in central Tunisia at least 42 prisoners were killed in a fire after one inmate set his mattress alight—one of several attempted escape bids as inmates apparently sought to take advantage of the chaos.

Ben Ali signed his resignation on Friday and fled to Saudi Arabia after a wave of protests sparked by the suicide of a 26-year-old university graduate prevented by police from selling fruit and vegetables to make a living.