Tunisia's prime minister appointed opposition figures to a new coalition government on Monday, trying to establish political stability after violent street protests brought down the president last Friday.
Prime Minister Mohamed Ghannouchi also said the government was committed to releasing all political prisoners, and that anyone with great wealth or suspected of corruption would face investigation.
Demonstrators took to the streets earlier in the day demanding that the ruling party of ousted President Zine al-Abidine Ben Ali give up power.
Some demonstrators said they would not accept members of the Ben Ali government as part of the new coalition. Security forces used water cannon and tear gas and fired shots in the air to disperse the protest, which ended peacefully.
The ministers of defence, interior, finance and foreign affairs will keep their jobs in the new government and opposition leaders including Najib Chebbi will have posts, the prime minister said.
Ghannouchi named Chebbi, founder of the Progressive Democratic Party (PDP) which opposed Ben Ali, as minister of regional development.
Opposition figures Ahmed Ibrahim and Mustafa Ben Jaafar will also have cabinet posts, Ghannouchi said.
Speaker of parliament Fouad Mebazza, sworn in as interim president, had asked Ghannouchi to form a government of national unity, and constitutional authorities said a presidential election should be held within 60 days.
Moncef Marzouki, a professor of medicine who leads the CPR Tunisian opposition party in exile in France, told Reuters separately he would be a candidate in a presidential election.
Before Ghannouchi spoke, about 1,000 people gathered in the capital's main boulevard in a demonstration against the ruling RCD party, chanting: "Out with the RCD!" and "Out with the party of the dictatorship!"
One demonstrator, Monji Amari, said: "We are here to say 'No'. We have had enough of this party of power. We do not want to see them any more. Together with Ben Ali they are responsible for the situation that we are in now."