Online activist group Anonymous said on Saturday it had downed the websites of dozens of Israeli state agencies and a top bank in protest over the Jewish state's deadly air assault on Gaza.
The hackers said their operation "OpIsrael" had either damaged or completely erased the sites of more than 650 private and public institutions that included the Bank of Jerusalem -- one of the country's main finance houses.
"Bank of Jerusalem database has been deleted," the group said in a tweet next to a link to the lender's non-functioning website.
It also claimed to have briefly downed the foreign ministry website in protest over an alleged Israeli threat to cut the Gaza Strip's Internet communications.
"For far too long, Anonymous has stood by with the rest of the world and watched in despair the barbaric, brutal and despicable treatment of the Palestinian people in the so called 'Occupied Territories' by the Israel Defence Force," Anonymous said in a statement.
"But when the government of Israel publicly threatened to sever all Internet and other telecommunications into and out of Gaza they crossed a line in the sand."
The group threatened Israel with the "unbridled wrath of Anonymous" if it went ahead with the Internet cable cut.
Israel's foreign ministry was not immediately available for comment on the threat, and no reference to the hack attack was made in official government statements on Saturday.
Israel has been pressing an intense aerial assault over the coastal Palestinian enclave as militants from the ruling Hamas movement and other groups have fired hundreds of rockets over the border.
The intensifying stand-off has also played out over the Internet.
Militants have used social networking sites such as Twitter to promise new attacks and take credit for specific strikes.
Meanwhile, Israeli defence officials have used Twitter to provide real-time warnings about incoming rockets and also make direct threats against Hamas.