"The site is suffering from an attack on its connection between the database and the web server," Roni Becher, of Avnet, said Tuesday. "At this stage we don't know how the attack was carried out exactly, and what can be done to defend against it. Overnight, we saw dozens of attempts to hack and attack Israeli websites."
A group of anonymous hackers also claimed on Twitter that it brought down other official sites, such as the Ministry of Finance website, The Jerusalem Post reported.
The Post said all the Internet sites appear to be back up and running.
During the weekend, hackers claimed to have broken into hundreds of Israeli Facebook accounts.
On Sunday, Becher said those attacks were basic and not unusual.