Hacking group Anonymous is posting secret documents it obtained from an Italian authority that looks after the country's IT infrastructure.

The group claims it received 8GB worth of data that had been stolen from the Italian National Computer Crime Centre for Critical Infrastructure Protection (CNAIPIC) network from a "source". However, just 100MB of the data has been leaked on the web so far, with Anonymous publishing the documents on the Pastebin website.

The documents include information from a number of global authorities such as the Ministry of Defence in Australia as well as firms including Gazprom and Exxon Mobile.

"#AntiSec strikes at Italy government," the hacking group said via on one of its Twitter feeds.

"Silent no more," they later added.

It is thought the attack is in retaliation for the arrest of three Italians earlier this month in conjunction with cybercrimes.

The attack on CNAIPIC is thought to be in retaliation for arrests of Italian members of Anonymous.

The CNAIPIC has yet to comment on the leaked data.