Talaat Hafez, secretary-general of the media office in the kingdom's banking authority, denied a report by the Israeli daily Yediot Ahronot that Israeli hackers were threatening to release the financial information they obtained if hackers continue to publish Israeli credit details on line.
Hafez was quoted by the Saudi online newspaper Sabq.org as saying that Saudi bank customers' financial information was safe and there was "no need for customers to be concerned" because Saudi banks' information networks were very secure.
Hafez also said officials had received no reports from Saudis about their data being breached.
The dueling reports underscored the hostile relationship between Saudi Arabia and Israel. Saudi Arabia does not recognize Israel's statehood.
The hacking issue surfaced after Yediot Ahronot's online edition, YNet, reported that hackers, identifying themselves as Group XP, claimed to have gained access to 400,000 Israeli credit card accounts in what was described as "a gift to the world for the New Year."
Days later, a hacker claiming to be a 19-year-old Saudi national, using the pseudonym OxOmar, posted online the credit card details and personal information of 6,000 thousand Israelis and said he had access to tens of thousands of other accounts. He said the "Zionist lobby" was behind covering up the size of the initial leak.
On Tuesday, the Hamas militant group praised the cyber-attack as "resistance" against Israel.
"We in Hamas bless this effort and urge Arab youth to activate and develop it," Hamas spokesman Sami Abu Zuhri said in Gaza.
Israeli officials said about 21,000 active credit card accounts in all were compromised. Banks said the cards were cancelled and new ones issued.
It was not possible to independently verify the claims by the hackers.
In apparent retribution for the cyber attacks, YNet reported that Israeli hackers inside and outside the country had obtained the records of thousands of credit cards used in Saudi shopping websites. One of the hackers, who was not identified, told the newspaper they would disclose the material if "the leaks continue."
YNet said it reviewed the information and can "confirm that at least some of the names on the list are real and match the rest of the details presented in the hacker' list." The website said it verified some of the information through Facebook pages and email accounts.
Over the weekend, Israeli Deputy Foreign Minister Danny Ayalon described the cyber-attacks as terrorism and warned that Israel would "retaliate forcefully."
On Monday, he found his own website had been attacked.
Israel's military chief, Lt. Gen. Benny Gantz, told a parliamentary committee Tuesday that Israel is poised to combat cyber terrorism.
"From our standpoint we are talking about a meaningful and even critical arena," Gantz said.
The army chief's comments were relayed by a meeting participant who, under committee guidelines, spoke on condition of anonymity.
Israeli cyber expert Gadi Evron said politically-motivated cyber attacks have taking place for the last 20 years. "You may know who your rivals are, but you may not necessarily know who is hacking you," said Evron, formerly in charge of Internet security for the Israeli government and now a research fellow at Tel Aviv University.
He said Israel, a high-tech powerhouse, is more prepared than most countries to deal with cyber attacks, but it must improve cyber security co-ordination with the private sector, which controls key infrastructure like Internet and cellular phone providers.
Israeli security officials said the country's Shin Bet internal security agency has a special unit that advises sensitive sectors considered vital to security, like public utilities, about Internet security. It recently added banks and cellphone companies.
"We are definitely going to see more and more sophisticated attacks," Evron said, while cautioning against an overreaction that panics the public.
"The sun will rise tomorrow. It's not the end of world yet," he said.
Associated Press writers Abdullah Al-Shihri in Riyadh, Saudi Arabia, and Amy Teibel and Daniel Estrin in Jerusalem contributed.