The Palestinian Hamas group in Gaza blamed Israel on Saturday for the killing in Tunisia this week of a Tunisian national it described as one of its drone experts, and threatened retaliation. Hamas's armed wing, the Qassam Brigades, said Mohammed Zawari, who was gunned down near the city of Sfax on Thursday, had been a member of the group for 10 years and had been supervising its drone program. Hamas, which rules the Gaza Strip, did not offer any evidence to support its accusation. A spokesman for Israeli Prime Minister Benjamin Netanyahu did not respond to a Reuters request for comment. Private radio station Mosaique FM reported that Zouari's body was riddled with 20 bullets, in what was believed to be a murder although authorities have not ruled out terrorism. According to Israel's Channel 10, a senior Tunisian journalist said Mossad had been tracking Zoari for quite some time, and was responsible for his assassination. A senior Tunisian court official in Sfax, Murad a-Turki, said police had found two pistols, silencers and four cars apparently used in the killing. The Lebanese Al-Akhbar newspaper reported Saturday that Zoari had also assisted Lebanese terror group Hezbollah in the development of drone technology.