Story highlights

"Muslim extremists" hacked his website, Deputy Foreign Minister Danny Ayalon says

He said his site has been restored after being out of service for only a short time

Twice last week, hackers released thousands of credit card numbers and other data

Israeli official: Private info that was released is potentially the most damaging breach

Jerusalem CNN  — 

Israeli Deputy Foreign Minister Danny Ayalon said Monday that his website was the latest target of a cyberattack, coming on the heels of two attacks last week by a purportedly Saudi-based hacker group.

In a statement on his Facebook page, Ayalon said “Muslim extremists” hacked into his website “to try and prevent me from continuing to do my work on behalf of the State of Israel, especially my online public diplomacy.”

“We will not be weakened nor silenced by such attempts,” Ayalon said, adding that his site has been restored after being out of service for only a short time.

Last week, the group claiming to be Saudi Arabian hackers posted the credit card information and other identifying data of thousands of Israelis online, prompting an international investigation.

The group first posted a message Tuesday that included claims that 400,000 credit card numbers had been published.

“Hi, it’s OxOmar from group-xp, largest Wahhabi hacker group of Saudi Arabia,” read a statement posted on an Israeli sports website the group hacked into. “We are anonymous Saudi Arabian hackers. We decided to release first part of our data about Israel.”

The Bank of Israel released a statement Tuesday saying that, based on information from credit card companies, only about 15,000 credit card numbers were exposed, and those cards were blocked for use in Internet and telephone purchases.

Thursday, the group claimed to have released another 11,000 credit card numbers and threatened to publish many more.

Yoram Hacohen, who heads the Israeli Law, Information and Technology Authority at the Israeli Ministry of Justice, told CNN in a phone interview Friday that he’s more concerned about the private information that was released, not the credit card numbers.

The publishing of information such as e-mail addresses, phone numbers, home addresses and passwords could lead to identification theft, he said.

Hacohen said the hacking is a criminal act against citizens of the world, since some of the information exposed belongs to Jews worldwide, not just Israelis.

Israeli authorities have begun a criminal investigation, including a computer forensic probe to search for electronic evidence to try to locate the group, Hacohen said. The theft of personal information is a criminal act under Israel’s Privacy Protection Law.

After last week’s attacks, Ayalon had said the incident was “a breach of sovereignty comparable to a terrorist operation and must be treated as such.” He also said that Israel “has active capabilities for striking at those who are trying to harm it, and no agency or hacker will be immune from retaliatory action.”

However, Hacohen acknowledged that in the digital world, offenders are very difficult to track, and authorities are asking for international help in the matter.

Prime Minister Benjamin Netanyahu created a National Cyber Directorate in 2011, noting the emergence of cyberattacks that could “potentially paralyze life systems – electricity, communications, credit cards, water, transportation, traffic lights.”

He said in December that the new agency – along with a rocket defense system and a physical fence – would help protect Israel against its enemies.

CNN’s Michal Zippori in Jerusalem contributed to this report