Tunisia's new national unity government was unveiled today in an attempt to halt the wave of violent protests that led to the overthrow of president Zine El Abidine Ben Ali.

Prime Minister Mohamed Ghannouchi, a long-time ally of Ben Ali, and several top ministers retained their posts in the shake-up.

Mr Ghannouchi also announced that political prisoners would be freed, among an array of measures aimed at loosening up a system that for decades was effectively under the single rule of Ben Ali's RCD party.

A key question was whether the changes would be enough to stabilise the country that has been reeling under continued unrest after Ben Ali fled on Friday - 23 years after he first took power.

Mr Ghannouchi, who has been premier since 1999 and has kept his post throughout the upheaval, said the current ministers of defence, interior and foreign affairs would stay.

Three opposition figures, including Nejib Chebbi, a founder of the opposition PDP party, will join the government.

Until new presidential elections are held, the country is being run by interim president Fouad Mebazaa, former speaker of the lower house of parliament, also a veteran of Tunisia's ruling party.

Mr Ghannouchi said all non-governmental associations that seek it would be automatically recognised, and all the restrictions on the Tunisian League for the Defence of Human Rights would be lifted.

Many opponents of Ben Ali's rule have taken to the streets to demand the new government not include of any remnants of his iron-fisted regime.

Earlier security forces fired tear gas to repel angry demonstrators ahead of the announcement.

A union leader upset at the prospect of a government full of old guard ministers, predicted growing demonstrations to press for an end to power positions for the RCD.

"It (RCD) left by the back door and is coming back through the window," said Habib Jerjir, of the Regional Workers' Union of Tunis. "We can't have militias in the streets and in the government.

Mr Ghannouchi said the government would create three new state commissions to study political reform, investigate corruption and bribery, and examine abuses during the recent upheaval.

He did not refer to the prospect of new elections, which under Tunisia's constitution must be called within 60 days. But some members of the opposition want more time, to allow the public to get know the choices in a country known for one-party rule - and possibly on the cusp of democracy.

Whatever emerges, the new leadership will first face the challenge of restoring order. Looting, gunbattles, and score-settling have racked the country since Friday, when a month of street protests against years of repression, corruption and a lack of jobs brought down Ben Ali.

Shops in the centre of Tunis remained shut today, and police were deployed in force. A semblance of normal daily life returned in other areas of the capital where shops, gas stations, pharmacies and supermarkets reopened. Many people returned to their jobs and others rushed to buy scarce stables like bread, fish and milk.

Hundreds of stranded tourists were still being evacuated from the country, and foreign airlines gradually resumed the flights that were halted when Tunisian airspace closed amid the upheaval.

Over the weekend, police arrested dozens of people, including the top presidential security chief, as tensions appeared to mount between Tunisians buoyant over Ben Ali's ouster and loyalists in danger of losing many perks.

Ex-presidential security chief Ali Seriati and his deputy were charged with a plot against state security, aggressive acts and for "provoking disorder, murder and pillaging," the TAP state news agency reported.

Fierce gunbattles broke out between the two groups around the presidential palace yesterday in Carthage on the Mediterranean shore, north of Tunis and near the Interior Ministry in the capital.

The protests began last month after an educated but jobless 26-year-old set himself on fire when police confiscated the fruits and vegetables he was selling without a permit. His desperate act - from which he later died - hit a nerve, sparked copycat suicides and focused anger against the regime into a widespread revolt.

Reports of self-immollations surfaced in Egypt, Mauritania and Algeria on Monday, in apparent imitation of the Tunisian events.