Close on the heels of the arrest hackers in Europe and the US, hackers groups LulzSec and Anonymous have announced they hacked into the website of Italy’s cyber police which they called Operation Italy and published classified information online.

The attack on Italian National Anti-Cybercrime Center for the Protection of Critical Infrastructure (CNAIPIC) is thought to be in retaliation for arrests of Italian members of Anonymous.

The hackers group are calling themselves "Legion of Anonymous Doom" breached into the website and published some of the hacked contents.

The hackers group is claimed to have stolen 8GB of leaked data but only provided links to few previews of their cache.

The information published so far relate to Italian government interactions with ministries and business groups in Australia, Belarus, Egypt, Russia and Ukraine.

Hackers said the documents represented only one percent of the total cache.

The attack on the CNAIPIC’s website has come after Anonymous and LulzSec avowal to continue their struggle for transparency following the arrest of fellow hackers.

The communications police unit of Italy admitted it had been hacked but did not confirm or deny the claims that the classified information has been stolen.

The group first became known for an attack on Sony and Nintendo video games followed by the CIA, the FBI and Rupert Murdoch’s media empire News Corp.

Hackers claiming membership of the Anonymous collective earlier this year launched cyber attacks on a variety of Italian government and business sites.