A mass cyber attack by hacker groups targeting Israel which began Saturday continued on Monday, but the damage was negligible, the Shin Bet domestic security agency said.

"As of noon on Monday, the state of alert continues and the efforts and activity to prevent the cyber attacks that began on Saturday night are ongoing," the agency said in a statement.

It said the Shin Bet and other agencies responsible for cyber security had "managed to locate and prevent attacks aimed at harming many websites and ISPs serving civilians."

The agency had recently issued a fresh set of security guidelines to government agencies and to the business sector, it said.

"So far, the incidents are at a low level and have not caused any damage to websites, civilian 'e-government' services or to the main communications firms.

"The sites which have been affected are generally private civilian websites with a very basic level of security," it said.

Over the weekend, hackers associated with the activist group Anonymous reportedly hit the websites of the ministries of defence, foreign affairs and education, among others, with cyber experts saying the damage was "more or less non-existent".

Last November, Israel was targeted by what it said was an "unprecedented" mass cyber-warfare campaign as it waged an eight-day operation against Gaza militants.

At the time, Anonymous claimed it had downed or erased the databases of nearly 700 Israeli sites in protest.