Tunisia's secular opposition said on Friday that the governing Islamists must quit power before they would join negotiations to resolve the country's worst crisis since its Arab Spring revolt, declaring otherwise the talks would be a waste of time. Opposition leaders said an agreement in principle by the Islamist party Ennahda on Thursday to start talks soon with the mediation of the country's powerful UGTT trade union federation was only a government attempt to buy time. Commentators said Ennahda's apparent concessions this week kindled hope that Tunisia, the birthplace two-and-a-half years ago of the Arab Spring revolts, might find a consensus to save its nascent democracy rather than see it collapse as in Egypt. However, as rival parties squabbled over the UGTT offer to mediate, opposition groups went ahead with plans for a large rally on Saturday outside the country's constituent assembly in Tunis to pressure the Islamist-led government to quit. "Any negotiation without the immediate dissolution of the government would be a waste of time," Taieb Baccouche, secretary general of the main opposition party Nida Tounes, said after meeting UGTT chief Hussein Abassi. Samir Bettaib, a leader in the "Salvation Front" grouping of several opposition groups, said: "Ennahda continues to manoeuvre ... the only initiative we accept is the announcement to dissolve the government immediately." Abassi, whose million-strong Tunisian General Labour Union gives him a central role in pressuring the two sides towards consensus, was due to hold another meeting with Ennahda chairman Rached Ghannouchi later on Friday.