A VICTORIAN man has lost a four-month battle to gain access to early drafts of a report on internet filtering that was used by the Federal Government to justify pressing ahead with its controversial web censorship plan.

The ISP Content Filtering Pilot Report, released in December last year, found it was possible to accurately block access to a list of banned web pages without major impact to internet speeds.

It was based on the results of a trial of filtering products with nine internet service providers (ISPs), conducted for the Government by Enex TestLab.

However 37-year-old electronic design engineer Cameron Watt, from Sunbury, northwest of Melbourne, believes the report did not include enough detail about how the tests were conducted.

"The final document I think lacks the detail I would have expected to be in there and the detail of previous ISP filtering tests," Mr Watt told news.com.au.

"ISP filtering is a fairly serious change in the way the internet has been dealt with by governments, especially in Western democracies, and I see it as something that needs robust public debate."

Five days after the report was released, Mr Watt lodged a Freedom of Information request with the Department of Broadband, Communications and the Digital Economy to access documents containing results of the trial.

The request was quashed by the department last month.

Among the documents requested by Mr Watt were drafts of the individual results for each ISP that participated in the trial, as well as draft versions of the consolidated results.

One of the draft versions of the consolidated results, dated last August, is marked as "anonymised" and is 36 pages longer than the 98-page report released to the public, according to information made available during the request process.

In a statement of reasons given for blocking Mr Watt's request, the department said the drafts contained commercially sensitive information and releasing them could harm its relationship with the internet industry.

"Protection of confidential material was a key element in the decision-making of several parties to participate in the pilot," the department said.

"Disclosure of confidential information accessed through the pilot and in preparation of the pilot report would cause a significant breach of trust.

"This may also inhibit the department's future access to such industry participation and expose the Commonwealth to litigation seeking substantial damages."

The department originally estimated the cost of processing Mr Watt's request at between $5524.12 and $7071.87, but charged him only $337.50 after its decision.

The department said even if names of participants were removed from the drafts, savvy readers may still be able to piece together the details.

"Information was presented in these draft documents in order to facilitate cross-reference and analysis in a way that was never intended to be reproduced in the final version," it said.

"This creates a high probability that, even should the names of third parties be removed, informed parties will infer or deduce specific results and potentially lead to erroneous interpretations or conclusions."

The department said the drafts were also exempt because they contained details of its internal deliberations.

"The disclosure of those deliberations would be against the public interest," it said.

A spokesperson for Communications Minister Stephen Conroy said the decision to block Mr Watt's request had been made after consultations with trial participants.

"A number of ISPs that participated in the pilot, some filter vendors and Enex, expressed concerns about the release of some or all of these working drafts because they contain material that is commercial-in-confidence," they said.

However the spokesperson said it was up to individual participants whether to release their own results: "Individual ISPs or filter vendors can release material relevant to them if they wish."

Responding to Mr Watt's concerns about the level of detail contained in the final report, Senator Conroy's spokesperson said it was not possible to make comparisons to previous internet filtering tests.

"The report followed the live pilot trial which was specifically related to the Government's ISP-level filtering policy," they said.

"Previous testing commissioned by the Howard government looked at issues not related to the policy, including dynamic filtering technologies."

Mr Watt is a member of online rights group Electronic Frontiers Australia, one of the most vocal critics of the Government's internet filtering plan, which would see ISPs like Telstra and Optus forced to block access to a secret list of banned web pages.

Mr Watt said the request was carried out "at arm's length" from the group and was funded privately.

The department accepted a request by Mr Watt for internal review of the decision earlier this month.

"That review is currently underway," said Senator Conroy's spokesperson.

The Government is expected to introduce legislation for its filtering plan later this year.

andrew.ramadge@news.com.au