Tunisians on Thursday mourned six policemen killed in a firefight with suspected jihadists, as long-awaited crisis talks faced fresh delay over opposition doubts about the ruling Islamists' readiness to quit.
The slain police were to be buried later Thursday in home towns around Tunisia, including in the central Sidi Bouzid region where Wednesday's clash broke out, amid rising anti-government sentiment within the security forces.
President Moncef Marzouki has declared three days of national mourning for the officers.
The powerful UGTT trade union confederation called a strike in Sidi Bouzid, the poor central town where the uprising that toppled strongman Zine El Abidine Ben Ali in 2011 first began.
Wednesday's violence came a week after two policemen were killed in Beja, west of the capital, also by a "terrorist" group according to the authorities, and as opposition protesters massed in central Tunis demanding the immediate resignation of the Islamist-led government.
A national dialogue, which is the centrepiece of a plan to end the political paralysis gripping the country since the July assassination of opposition MP Mohamed Brahmi, has been put back to Friday.
The roadmap, drawn up mediators led by the UGTT, ran into trouble when Islamist Prime Minister Ali Larayedh gave what the opposition described as an "ambiguous" commitment to step down in a speech late on Wednesday.
"We repeat today our commitment to the principle of relinquishing power in line with the different phases envisaged in the roadmap," Larayedh said after an emergency cabinet meeting.
"We will not submit to anyone except the interests of the country," he added, in a heavily delayed statement that was supposed to precede the launch of the national dialogue.
The UGTT chief said the premier needed to clarify his comments to get the dialogue back on track.
"We are going to hold more consultations with the prime minister in order to get more clarifications on his speech," Houcine Abassi said.
"We've decided that the national dialogue will begin on Friday," he added.
The opposition had been waiting for a "clear commitment" by Larayedh to resign within three weeks, as stipulated in the roadmap drawn up by mediators and agreed to by his Islamist party Ennahda, to allow the national dialogue to begin.
According to the roadmap, the talks must lead within three weeks to the formation of a caretaker cabinet of technocrats.
Negotiators will also have one month to adopt a new constitution, electoral laws and a timetable for fresh elections -- key milestones in a transition that has effectively been blocked by wrangling between the Islamists, their coalition allies and the opposition.
Rising police casualties
Commenting on the latest violence, Larayedh insisted Tunisia was "in the process of defeating terrorism... despite the sacrifices," and that the security forces were pursuing the remaining militants.
In addition to the six policemen and one militant killed in Sidi Bouzid, another policeman also died on Wednesday in the north of the country in circumstances that are not yet clear, the interior ministry said.
The deadly clashes over the past week have highlighted opposition complaints of inadequate action by the Islamist-led government to rein in jihadist groups, who have been accused to the killings of both Brahmi and another opposition MP slain in February.
Dozens of police trade union activists drove Larayedh and Marzouki away from a memorial service last Friday for the policemen killed in Beja.
The defence ministry has admitted it lacks the resources to combat militant groups and has struggled to contain them.
The planned national dialogue between the ruling Islamists and the opposition was due to begin exactly two years after Ennahda emerged as the largest party in parliamentary elections that followed Ben Ali's overthrow.
The Islamist group was heavily repressed under the Ben Ali regime.
But since its triumph at the polls, the party has been weakened by accusations that it has not done enough to fix Tunisia's ailing economy and improve living standards, as well as failing to stem jihadist violence.