The Israeli Ynet news website said the hackers called the cyber attack a "gift to the world for the New Year" that they hoped "would hurt the Zionist pocket".

They claimed to have compromised 400,000 credit-card holders, but Israel's central bank said only about 15,000 active cards were affected.

Cyber expert Gadi Evron said that it would be almost impossible to verify the attackers were Saudi.

Evron, who once oversaw security for the Israeli government Internet provider, said the attack was "nothing special" technically and was "mundane".

He added: "Potentially, such attacks could be devastating. But this is not one of them."