JERUSALEM — The credit card details of more than 20,000 Israelis were exposed on the Internet in two waves this week by a hacker or team of hackers who said they were Saudis.

Some Israeli officials described the release of the information as cyberterrorism. Others said that it was too early to define the nature of the attack because there was still no way yet to confirm who did it.

“You have to look at the facts: somebody is publishing information about Israelis in order to harm the economy,” Yoram Hacohen, the head of the Israeli Law, Information and Technology Authority at the Justice Ministry, told Army Radio on Friday. He said the hacker or hackers “could be a citizen of any country in the world” and that “investigations in the digital realm” were no trivial matter.

The initial reports on Tuesday morning were considerably more alarming: that the details of 400,000 credit card holders had been posted online by a hacker identifying himself as a 19-year-old from Riyadh, Saudi Arabia, who used the Web name 0xOmar. But the three credit card companies that were affected said that many of the card numbers and details had been listed multiple times and that some were incorrect.