The crucial talks aim to pave the way for a transitional government and end the political deadlock in the country.
Protests which erupted following the assassination of an opposition leader put the country in crisis and chaos for weeks. The North African country had spurred the “Arab Spring” revolts across several countries in the Middle East since 2011.
The hard-won dialogue began despite a last-minute dispute, delegates said.
The dispute emerged as delegates started to gather at the Palais des Congres for a symbolic ceremony during which the ruling Ennahda movement was to declare its readiness to resign.
Ennahda and the opposition were also due to pledge allegiance to a roadmap on Tunisia’s political future at Saturday’s meeting, with talks between the two sides due to begin in earnest next week.
But the opposition accused the moderate Islamist movement Ennahda of refusing to sign the roadmap drafted by mediator to end the crisis triggered in July by the assassination of prominent MP Mohamed Brahmi.
“We don’t see why Ennahda is refusing to sign. This is a sign of bad intentions and breeds a climate of mistrust,” said Mongi Rahoui of the opposition National Front.
“So far we have not started the dialogue and there could be a delay,” he told AFP.
A member of Ettakatol, a center-left party allied with Ennahda, accused the opposition of imposing last-minute conditions, but declined to give details.
“There is a real problem of trust,” Mouldi Riahi told Agence France-Presse.
Earlier, the head of the Tunisian League for Human Rights, one of four mediators between Ennahda and its opponents, said a signing ceremony would go underway as planned.
Ennahda “must pledge the government’s resignation,” Abdessatar Ben Moussa added.
The roadmap sets a three-week deadline to form a government of independents to replace the Ennahda-led government, after the launch of dialogue with opposition parties.
It also sets a four-week deadline for adopting a new electoral law and pave the way again to the much-delayed adoption of a new constitution.
Earlier this week, Ennahda and the secular opposition agreed on a blueprint for talks, also drafted by the main UGTT trade union, the employers’ organization Utica and the bar association.
Asked if the launch of the dialogue could be delayed, UGTT spokesman Sami Tahri told Radio Shems FM: “Everything is possible.”
Ennahda has been accused of mismanaging the economy and failing to rein in Tunisia’s jihadist movement, which is blamed for murdering Brahimi and opposition MP Chokri Belaid, another prominent secular politician killed six months earlier.
Saturday’s ceremony was attended by President Moncef Marzouki, Prime Minister Ali Larayedh, parliament speaker Mustafa Ben Jaafar, as well as party leaders.
Political activity in Tunisia has ground to a halt since Brahmi’s murder, holding up the formation of stable state institutions more than two and half years since the 2011 uprising that topped longtime strongman Zine El Abidine Ben Ali and touched off the Arab Spring.
On the eve of Saturday’s scheduled launch, a newspaper took a swipe at Tunisia’s political actors and expressed skepticism at the outcome.
“Tunisians are hanging on the words of political actors, protagonists in a national dialogue... Will this dialogue lead to a saving solution?” asked the francophone daily Le Quotidien.
“It’s like watching a Mexican soap opera, but without the romance,” it quipped of the two-month-long standoff.