A Tunisian opposition party leader who had been critical of the Islamist-led government and radical Muslim violence has been shot dead.
Chokri Belaid, leader of the Unified Democratic Nationalist party, was shot outside his home in Tunis on Wednesday morning and died in hospital shortly after.
President Moncef Marzouki cut short a visit to France and cancelled a trip to Egypt scheduled for Thursday after the killing, which triggered a 1,000-strong protest outside the interior ministry.
Chanting for the fall of the Islamist-led government, demonstrators shouted "Shame, shame Chokri died", "Where is the government?", and, "The government should fall".
The prime minister, Hamadi Jebali, who heads the Ennahda party-led government, which won Tunisia's first post-Arab spring election in 2011, said: "The murder of Belaid is a political assassination and the assassination of the Tunisian revolution. By killing him they wanted to silence his voice."
Belaid was an outspoken critic of the coalition government. His small party co-founded the Popular Front, a leftist alliance preparing to compete in the elections this year.
"Chokri Belaid was killed today by four bullets to the head and chest ... doctors told us that he has died. This is a sad day for Tunisia," Ziad Lakhader, a leader of the Popular Front, told Reuters. Other party sources confirmed his death.
The reason for the killing is unclear, but it comes as Tunisia struggles with social and religious tensions after its longtime dictator was overthrown in an uprising two years ago that set off revolts across the Arab world.
The murder comes amid reports of intimidation and violence against opposition groups, and days before an official commission of inquiry is due to report its findings on an attack against a trades union rally in December.