Kamel Ghadghadi, a senior member of Tunisia’s banned Islamist group Ansar al-Sharia, has reportedly been killed during a police raid.
A security source said seven Islamist militants and a Tunisian policeman were killed in a gun battle after police raided a house in Tunis.
Ghadghadi was a suspect in the assassination of two Tunisian opposition leaders almost exactly one year ago.
Since last year, Tunisian armed forces have cracked down on the hardline Islamist Ansar al-Sharia faction. Washington has listed it as a terrorist organisation. Its leader has declared allegiance to al Qaeda.
Tunisia celebrates a new constitution on Friday. French President Francois Hollande and other dignitaries have been invited to a ceremony to mark the North African country’s progress to democracy.