TUNIS: The suspected killer of leftist opposition figure Chokri Belaid, a leading critic of Tunisia's ruling Islamists whose murder sparked a political crisis, was arrested on Monday, police sources said.

They said the suspect was arrested along with an alleged accomplice, both members of the radical Muslim Salafist movement. The main suspect, a 31-year-old furniture maker, was arrested in the Carthage suburb of Tunis.

The second man was allegedly the getaway motorbike rider for the lone, hooded gunman who shot dead Belaid, 48, at close range in front of his Tunis home on February 6, two police officers told AFP.

They said the arrests were carried out on the strength of the testimony of a woman who had witnessed the killing and has since been placed under police protection.

Several online media also reported the two arrests, but the interior ministry spokesman was unreachable for comment.

Interior Minister Ali Larayedh, who has been tapped to form a new government in the face of the deepening crisis sparked by Belaid's killing, said last week that arrests had been made.

"The investigation has not led yet to identify the killer, those behind the murder and its motives," said Larayedh, refusing to elaborate or disclose the number of arrests.

Belaid's family has blamed the ruling Ennahda party for being behind the killing, an accusation the Islamists have vehemently denied.

The assassination triggered days of unrest as people took to Habib Bourguiba Avenue, epicentre of the 2011 uprising that toppled ex-dictator Zine El Abidine Ben Ali, exacerbating a long-running political crisis in Tunisia.

On the day of the murder, prime minister Hamadi Jebali proposed the formation of a government of technocrats as a way out of the crisis. But the initiative was rejected by his own Ennahda party, leading to his resignation.