Tunisia's labour unions have called for a general strike on Friday to protest against the killing of opposition politician Shokri Belaid.
Al Jazeera's Hashem Ahelbarra, reporting from Tunis, said the decision to strike was a "significant move forward".
"The last general strike took place in 1978 and basically, this is something that crippled Tunisia and over the past three decades, the government have always tried to maintain good ties with the unions," said Ahelbarra.
The tension could escalate on Friday as high turnout is expected for Belaid's funeral.
"We in Ennahda believe Tunisia needs a political government now. We will continue discussions with others parties about forming a coalition government"
- Abdelhamid Jelassi,
The police and army have been put on alert to prevent any outbreaks of violence and to "deal with any troublemakers" announced the presidential spokesman Adnan Mancer in a press conference late on Thursday.
The strike also comes on the back of the country's ruling Islamist Ennahda party rejecting Prime Minister Hamdi Jebali's proposal to dissolve the government and install a cabinet of technocrats in a bid to restore calm after Shokri's assassination.
"The prime minister did not ask the opinion of his party," said Abdelhamid Jelassi, Ennahda's vice-president.
"We in Ennahda believe Tunisia needs a political government now. We will continue discussions with others parties about forming a coalition government."
Ennahda won 42 percent of seats in the first post-Arab uprising elections in October 2011 and formed a government in coalition with two secular parties, Marzouki's Congress for the Republic and Ettakatol.
Tunisian police meanwhile fired teargas on Thursday to disperse hundreds of people near the Interior Ministry in Tunis as violent protests over Shokri's killing continued for a second day.
Demonstrators were throwing stones and chanting slogans calling on Jebali to resign.
Jebali had announced he was dissolving the government in the immediate aftermath of Shokri's death.
Al Jazeera's Ahmed Janabi, reporting from Tunis, said that security reinforcements have arrived at the French embassy in the heart of Tunis, where protesters have gathered.
"Police continue to chase demonstrators away from the embassy's vicinity. Anti-riots forces chased demonstrators in the allays surrounding the embassy," said Janabi.
Hundreds of opposition protesters also clashed with police outside the governor's office in the central Tunisian town of Gafsa, an AFP news agency journalist reported.
|Anti-government protesters clashed with police, who retaliated with tear gas [Ahmed Janabi/Al Jazeera]
The state news agency TAP also reported clashes in cities across the country, with police resorting to tear gas and warning shots. In the northwest town of Boussalem, demonstrators set fire to a police station.
No one has claimed responsibility for the killing of Belaid, a lawyer and secular political figure, who was shot by a gunman as he left home for work on Wednesday.
Belaid had been critical of Tunisia's leadership, especially the Ennahda party that dominates the government.
He had accused authorities of not doing enough to stop violence by ultraconservatives who have targeted mausoleums, art exhibits and other things seen as out of keeping with their strict interpretation of Islam.
As the protests intensified, four Tunisian opposition groups, including the Popular Front, of which the Belaid's Democratic Patriots is a component, announced they were pulling out of the national assembly.
Moncef Marzouki, the Tunisian president, cut short a visit to France and said he would fight those who opposed the political transition in his country.
The assassination comes as Tunisia is struggling to maintain stability and revive its economy after its longtime dictator was overthrown in an uprising two years ago.
Source: Al Jazeera and agencies