Tunisia: Many dead in jail unrest after Ben Ali exit
Nearly 50 people are reported to have been killed in shooting and rioting at two Tunisian prisons, amid continuing unrest following the removal of President Zine al-Abidine Ben Ali.
There was looting and gunfire in the capital, Tunis, after the celebrations marking his flight to Saudi Arabia.
Troops are patrolling the city centre and a state of emergency is in force.
The violence came as the Speaker of parliament, Foued Mebazaa, took over as interim president.
He said he had asked Prime Minister Mohammed Ghannouchi - who had earlier said he was in temporary charge - to form a national unity government.
In a televised address, Mr Mebazaa said all political parties including the opposition would be consulted.
"All Tunisians without exception and exclusion must be associated in the political process," he said after taking the oath.
The Constitutional Council had earlier declared he should lead the country. Under the constitution a new presidential election must be held within 60 days.
The BBC's Wyre Davies, in Tunis, says people are now waiting for some indication that the interim administration is prepared to bring in widespread economic and political changes.
Saturday's deadliest incident appears to have been in the resort of Monastir where a fire swept though a prison, killing at least 42 people.
The identities of the victims and the cause of the fire are still unclear. Reports said inmates had been attempting to escape.
"The whole prison is on fire, the furniture, mattresses, everything," an eyewitness in the city, about 160km (100 miles) south of Tunis, told Reuters news agency.
In Mahdia, further south, at least five people were killed after soldiers opened fire on prisoners at the town's jail, a senior official told the Associated Press. The official said the prison director then freed hundreds of other inmates to avoid more bloodshed.
There were reports of violence and escape attempts at several other jails.
In Tunis, soldiers and police exchanged fire with gunmen outside the interior ministry, media reports said.
The Associated Press said its reporters had seen "two bodies lying on the ground" - it was not clear who they were, or whether they were dead or injured.
Troops and tanks are protecting official buildings and the streets are largely deserted, correspondents say.
Overnight looting continued into Saturday in the city's suburbs, with French-owned supermarkets among the properties targeted. The city's main railway station has been badly damaged by fire.
Tunis Carthage International Airport, which was closed amid Friday's unrest, re-opened on Saturday. Hundreds of tourists and other foreigners have been trapped there. Many have been airlifted home.
In the past four weeks, protests have swept the country over unemployment, food price rises and corruption. Security forces used live ammunition against protesters and dozens of people died.
The African Union has condemned what it called "excessive use of force against the demonstrators".
Mr Ben Ali, who had been in power for 23 years, conceded power on Friday after the unrest culminated in a giant rally against him in Tunis.
He flew out of Tunisia with his family and, after the French government rejected a request for his plane to land there, was allowed to refuel in Sardinia before landing in Jeddah, Saudi Arabia.
A Saudi palace statement said: "Out of concern for the exceptional circumstances facing the brotherly Tunisian people and in support of the security and stability of their country... the Saudi government has welcomed President Zine al-Abidine Ben Ali and his family to the kingdom."
French President Nicholas Sarkozy said on Saturday the Tunisian people had "expressed their democratic will" and called for free elections as soon as possible.
Britain condemned the violence and looting and urged restraint from all sides.
There has been little official reaction from Tunisia's Arab neighbours to the events. On Saturday the Arab League called on Tunisia's political forces "to stand together and unite" to maintain peace.
The UK, the US and France are among the countries advising against non-essential travel to Tunisia.
Mr Ben Ali was only Tunisia's second president since independence from France in 1956. He was last re-elected in 2009 with 89.62% of the vote.