GAZA CITY: Palestinian group Hamas said Saturday a Tunisian engineer murdered in the North African country was one of its leaders, accused Israel of the killing and vowed to avenge him.

Mohammad Zaouari, a 49-year-old engineer, was murdered at the wheel of his car outside his house in Tunisia's second city, Sfax, on Thursday.

Al Qassam Martyrs Brigade, the armed wing of Hamas that controls the Gaza Strip, told AFP on Saturday that drone expert Zaouari was killed by "Zionist treachery", referring to Israel.

It said Zaouari had worked for the "resistance" for 10 years, and announced a day of mourning.

"Zaouari's assassination in Tunisia is aggression against the resistance, and Al Qassam Brigades and the enemy should know that the blood of the leaders will not be wasted and lost in vain," it said in a separate statement.

Tunisia's Islamist Ennahdha movement has called for an investigation into the killing, which it said posed a threat to the country's stability.

Authorities in Tunisia have said at least five suspects have been detained in Sfax, Tunis and Djerba, and four vehicles seized along with two guns equipped with silencers.

Private radio station Mosaique FM reported that Zaouari's body was riddled with 20 bullets.

Israel has ignored the Hamas allegation, despite its record of assassinating members of militant groups abroad, including in Tunisia.

In 1988, the head of the Palestine Liberation Organisation military wing Khalil Al Wazir, better known as Abu Jihad, was killed by Israeli commandos in Tunisia with another senior PLO figure, Saad Sayil.

Agents from the Jewish state's spy agency Mossad failed in 1997 in an attempt to kill Hamas leader Khaled Meshaal in Jordan with poison.