Riot police fired tear gas and clashed with protesters on Tuesday at a small protest rally against Tunisia's new government in the centre of the capital, AFP reporters on the ground saw.
Around 100 protesters chanted slogans against the RCD (Constitutional Democratic Rally) party of ousted president Zine El Abidine Ben Ali. "We can live on bread and water alone but not with the RCD," they said.
Riot police dispersed the rally, one of several expected on Tuesday.
Tunisia new transition government braced for protests Tuesday as it unveiled unprecedented freedoms but also left powerful posts in the hands of old regime figures braced for protests.
Prime Minister Mohammed Ghannouchi was one of eight ministers staying on from the previous government of disgraced president Zine El Abidine Ben Ali, who fled on Friday in the Arab world's first such popular revolt.
Ghannouchi said that the ministers remaining, including the defence and interior ministers, had acted "to preserve the national interest."
"They kept their posts because we need them at this time," Ghannouchi said on French radio Europe 1. "All of them have clean hands," he said.
"Thanks to their dedication they managed to reduce certain people's capacity to do harm. They manoeuvred, delayed and bought time to preserve the national interest," he said.
Police have clashed with Ben Ali loyalists in the capital in recent days.
Ghannouchi also said that exiled Islamist leader Rached Ghannouchi, who is not a relative of the prime minister, would only be able to return to the North African state from Britain once an amnesty law had been approved.
The popular Islamist was sentenced to life in prison under the old regime for plotting against the state.
As he unveiled the new government and promised parliamentary and presidential elections within six months on Monday, Ghannouchi announced complete media freedom and the release of all political prisoners.
But many Tunisians remained unconvinced by the new leadership.
"This isn't a transitional government, it's the return of the old regime in a different form," said Mustapha Hammami, a trade unionist in a cafe in the historic Medina in the centre of the capital Tunis.
On Facebook, a key instrument in spreading the word about protests, the popular "Tunisian Revolution" page called for rallies against the government in the capital Tunis and the cities of Sousse and Sfax.
"The RCD, the party of dictatorship and the symbol of totalitarianism and tyranny, is still in business," one Internet user wrote on Facebook.
Another Facebook post read: "The dictator has fallen but the dictatorship not yet. Tunisians have to continue their mission."
The exiled opposition earlier branded the new government a farce.
Interior Minister Ahmed Friaa on Monday said 78 people had been killed in the protests, several times higher than the last official death toll, and said losses to the economy amounted to €1.6 billion ($2.2 billion).
The losses are equivalent to around four per cent of Tunisia's GDP.
Thousands of foreign tourists, a key source of revenue, have fled Tunisia in recent days and normal business activity has been disrupted.
The interior ministry in central Tunis remained under heavy guard following protests on Monday in which hundreds of people marched through the city centre to demand the abolition of the RCD party of ousted leader Ben Ali.
The protest was broken up by riot police as any public gatherings are still banned under the strict rules of a state of emergency declared by Ben Ali. A dusk-to-dawn curfew also remains in place.
The president fled to Saudi Arabia after 23 years in power and some of his closest allies including former security chief Ali Seriati have been arrested.
On Tuesday, Ghannouchi said that those responsible for repressions during the past month of protests would be put on trial.
"All who were involved in those massacres will answer to justice," he said.
Britain's Foreign Secretary William Hague urged the new government in Tunisia to respect the constitution and human rights and to work "quickly and decisively" as it takes control.
"The elections that are now scheduled in our view should be free and fair elections and that should be clear to the world," Hague said.
The protests against Ben Ali escalated after a 26-year-old graduate set himself on fire in a protest against the authorities for preventing him from selling fruit and vegetables to make a living.
There has been a spate of apparent copycat public suicide attempts in other countries including Algeria, Egypt and Mauritania.