Tunisia has announced the first arrests relating to the murder this month of a prominent leftist opposition, even as politicians struggle to find a replacement prime minister, two days after Hamadi Jebali quit upon failing to form a cabinet of technocrats.
The consultative council of Ennahda was to meet on Thursday to choose a successor to Jebali, the ruling Islamist party's number two, who ruled himself out following suggestions he might be reappointed premier.
Jebali resigned on Tuesday after his plan to form a non-partisan government, announced in the wake of public outrage over the February 6 assassination of Shokri Belaid, was rejected by his own party.
Against this backdrop of political uncertainty, Ali Larayedh, Tunisia's interior minister, said on Thursday there had been arrests in the murder inquiry.
"The investigation has progressed to the point that suspects have been arrested," he said, without specifying the number of people detained.
"The investigation has not led yet to identify the killer, those behind the murder and its motives."
Belaid's assassination plunged Tunisia into its worst political crisis since the 2011 uprising that toppled Zine El Abidine Ben Ali, raising political tensions and exposing divisions within Ennahda between moderates and hardliners.
The party's spokesman Nejib Gharbi was quoted as saying by the official TAP news agency, with four candidates being considered to head the new government.
"Nothing has been decided yet, but there are four candidates for the post of prime minister - Ali Larayedh [the interior minister], Mohamed Ben Salem [agriculture], Noureddine Bhiri [justice] and Abdellatif Mekki [health]."
Ennahda later said Jebali, who is considered a moderate, had turned down an offer to head the new government, after senior Ennahda members, including its leader Rachid Ghannouchi, said the party was seeking to reappoint him.
The failure to form a new government comes amid deadlock over the drafting of a constitution, with parliament divided over the nature of Tunisia's future political system 15 months after it was elected and more than two years after the revolution.
Ennahda said it was "in the process of pursuing consultations internally and with its partners to present the president of the republic with the name of a successor to Jebali before the end of the week".
Belaid's family accused Ennahda orchestrating his murder, a charge it strongly denies.
The killing also prompted deadly street protests and strikes, which Jebali attempted to defuse by announcing plans for a non-partisan cabinet of technocrats to lead Tunisia into early elections.