Hacking group Anonymous has launched a series of cyber attacks against websites in Israel.

Anonymous announced its attacks via Twitter

Data bombardments briefly knocked some sites offline and led to others being defaced with pro-Palestinian messages.

The OpIsrael campaign was launched by the hacking collective in retaliation for attacks on Gaza.

The cyber attacks come as the Israeli army updates its web campaign adding "achievements" and "badges" for regular visitors.

Propaganda war

Anonymous said it had launched the OpIsrael campaign following threats by the Israeli government to cut all Gaza's telecommunication links. This, said the group in a statement posted to the AnonRelations website, "crossed a line in the sand".

"We are ANONYMOUS and NO ONE shuts down the Internet on our watch," it said.

The group warned the Israeli government not to cut off telecom and web links and urged it to end military operations in Gaza. If the attacks did not end, Israel would feel the group's "full and unbridled wrath".

Hours after the statement was launched, Anonymous posted a list of 87 sites it claimed had been defaced or attacked as part of OpIsrael. Many of the sites had their homepages replaced with messages in support of Hamas and the Palestinians.

Anonymous also produced a package of information for people in Gaza detailing alternative ways for them to communicate if net and other telecommunication links were cut.

At the same time as the Anonymous attacks were being carried out, the Israeli Defence Force re-started tools on its blog that reward people for repeat visits and interacting with the site.

Called IDF Ranks, the tools add a "game" element to the blog and reward repeat visitors with points. When visitors have amassed enough points they get a virtual military rank.

A visitor who goes to the site 10 times gets a "consistent" badge and someone who does lots of searches gets rewarded with the "research officer" rank.

The army said the rank system was turned off briefly as its social media sites had received very heavy traffic. On Wednesday, it began a live feed about its military operation against Hamas in the Gaza Strip.

Similarly, Hamas has been giving running commentaries on its mortar and rocket attacks on Israeli targets via Twitter.