France on Wednesday condemned the murder of Tunisian opposition leader Shoukry Belaid and expressed serious concern about a surge in political violence in the North African country.

"This murder robs Tunisia of one of its most courageous and free voices," President Francois Hollande said hours after Belaid, a harsh critic of Tunisia's Islamist-led government, was shot dead as he was leaving his home.

"Throughout his public life, Shoukry Belaid fought for freedom, tolerance and the respect of human rights with a deeply rooted conviction that dialogue and democracy should be at the heart of the new Tunisia," Hollande said in a statement.

"It is this message of unity and the rallying of Tunisians to the cause of fundamental freedoms that his assassins wanted to destroy."

Hollande called on all political players to respect the ideals that led to the 2011 overthrow of former dictator Zine El Abidine Ben Ali.

"France is very concerned by the increase in political violence in Tunisia and calls for the respect of the ideals of the people expressed during the revolution."

Belaid's family have accused Ennahda, the Islamist party that heads Tunisia's coalition government, of being behind the murder.