Anonymous is preparing to reveal 40GB of data its members say came from an Australian internet service provider (ISP) and contains “600k+” of customer data.

The Reg understands a “sample leak” will be released later today and that the organisation will take care to protect individuals' personal details.

The activist collective yesterday took credit for a series of defacements of Queensland government websites and has since contacted other media outlets, telling them that it intends to release customer data from an Australian ISP.

The @Op_australia Twitter feed recently promised it is “almost there” on "something big". Comments on an Anonymnous-aligned IRC channel offered the mention of 600,000 customers and references to the sample leak

The 600,000 figure means the data almost certainly comes from one of Australia's largest ISPs. Telstra and Optus are both known to have millions of subscribers, while iiNet has stated it has 1.3 million.

Among smaller ISPs, TPG's most recent half year report says it has 567,000 subscribers, placing it ahead of the likes of Exetel, Adam Internet and Netspace. iPprimus is probably also below the 600,000 customer threshold, making it likely that Anonymous will embarrass Telstra, Optus or iiNet … with TPG also a chance of hitting the headlines for all the wrong reasons. ®