"I'm telling them to die of their own fury," said the sheikh. "They are trying to disfigure the image of Islam and Muslims.
This time the victim is the Muslim militant group Hamas, with visitors to its home page being diverted to a hard-core pornography site called Hot Motel Horny Sex Sluts.
Sheikh Ahmad Yassin, spiritual leader of the political wing of Hamas, accused Israeli intelligence of being behind the hack.
"I'm telling them to die of their own fury," said the sheikh. "They are trying to disfigure the image of Islam and Muslims.
"These are the people who are shedding our blood and massacring our people every day, so it is not difficult for them to do something like this. As much as their anger and fire rises, they will try all and crazy ways to extinguish it."
Sheikh Yassin said Hamas would seek advice from internet specialists to block any further hacking attempts.
Hackers at war
Middle East "hacktivism" - as political hacking is called - has been a common feature of the past five months, during the Palestinian uprising to protest against Israel's occupation of the West Bank and Gaza.
There have been numerous successful and unsuccessful hacking attempts - many of them recorded on the computer security site Attrition.com - and website administrators on all sides are reported to have been busy defending their sites against attack from enemy hackers.
In November, an anti-Israeli hacker managed to penetrate the site of one of Washington's most powerful lobbying organisations, the American-Israeli Public Affairs Committee (Aipac), replacing it with critical e-mails from Aipac's own database, as well as publishing credit card numbers and e-mail addresses of Aipac members.
"The hack is to protest against the atrocities (sic) in Palestine by the barbarian Israeli soldiers and their constant support by the US Government," the raider - Doctor Nuker, founder of the Pakistan Hackerz Club - wrote.
Hackers have also targeted the websites of Israel's Parliament, its foreign ministry and an Israeli internet provider, as well as several sites run by the Hezbollah guerrillas.
But hacktivism does not always seem to have the desired effect - just before Israel's election, the campaign website of Ariel Sharon was replaced temporarily with pro-Palestinian material parodying Sharon's site under the headline "the world's biggest murderer".
He went on to win the election by a landslide and was due to be sworn in on the day after the Hamas hack was reported.