The military wing of Hamas which rules Gaza sent threatening text messages to Israelis on Saturday, 10 years after the Palestinian Islamist movement's spiritual leader was killed in an Israeli air strike.
Israelis, as well as foreign reporters in Israel, received messages reading: "If Gaza will be attacked the life of the Zionists will be hell" and "In the next war all the Land of Palestine will return".
A Hamas source told AFP it was the work of the Ezzedine al-Qassam Brigades, timed to coincide with the anniversary of the killing of Sheikh Ahmed Yassin.
"Al Qassam has chosen you to be the next Shalit," another message read, referring to Israeli soldier Gilad Shalit, who was abducted and held in Gaza for five years until Hamas freed him in exchange for more than 1,000 Palestinian prisoners.
The messages were sent from different cell phones. The owner of the only one who answered an AFP call was an Israeli man who said his line had been hijacked.
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The email account of an Israeli security-oriented newsletter, IsraelDefence, was also hacked and an email posted on Yassin's killing.
"We don’t forget the blood of our sheik, We swear again to take revenge, and this time by taking off the head of your leaders," read an email.
"Zionist killed our sheik by missile and now our missile can hit every corner of Zionist state," it read, signing off as "Sheikh Yassin's Followers".
Ahmed Yassin, who was founder and spiritual leader of Hamas, was assassinated in an Israeli air strike in 2004.
An Israeli police spokeswoman said she was unaware of the hacking incidents and that no complaint had been filed.
Israeli news website ynet said Hamas had sent similar messages during past conflicts with Israel.