Former Australian senator Rex Patrick has won a ruling allowing the public to attend unclassified portions of a hearing concerning records linked to Australia’s 2004 spying operation in Timor-Leste. The administrative review tribunal decided on Friday that those sessions of the three-day hearing scheduled for late November must be open, rejecting the commonwealth’s request to conduct them behind closed doors.

Patrick, now a transparency advocate, is seeking cabinet documents from 2004 held by the National Archives of Australia. The government maintains a position of neither confirming nor denying that the bugging occurred or that relevant records exist. The Australian Secret Intelligence Service, known as Asis, argues that confirming or denying the documents could damage national security and Australia’s relations with other countries.

The records would concern Australia’s approach to negotiations over control of the Timor Sea after Timor-Leste gained independence from Indonesia in 2002. Those talks determined the countries’ shared access to the Greater Sunrise gasfields, whose resources are estimated to be worth more than $50bn. The 2004 operation involved Asis personnel placing listening devices in important Timor-Leste government offices to learn its negotiating limits, tactics and differences of opinion within cabinet.

Classified portions of the November hearing will remain closed. Government lawyers had sought to exclude journalists and the public from the unclassified sessions as well, proposing instead to release a transcript after intelligence officials reviewed it. Deputy chief solicitor Justin Davidson argued that the stakes were high and that preventing an intelligence official from inadvertently revealing sensitive information would be nearly impossible.

Tribunal deputy president Peter Britten-Jones rejected that argument, finding that the officials involved had sufficient qualifications and experience to avoid disclosing secrets. He described the risk of accidental disclosure of protected material as negligible. Asis deputy director general Ewan McMillan and Department of Foreign Affairs and Trade deputy secretary Michelle Chan are due to testify. Patrick criticised the secrecy surrounding an operation he said was already widely known.

The case follows Patrick’s earlier effort to obtain records about Australia’s negotiating position. In 2021, he challenged extensive redactions to a cabinet submission from 2000 and a related minute. The tribunal subsequently released a less heavily censored document showing cabinet’s concern that Timor-Leste’s independence would invalidate Australia’s agreement with Indonesia for an equal division of revenue from Timor Sea reserves.

Australia secured a 50/50 division of the Greater Sunrise fields in 2006, benefiting the multinational joint venture led by Woodside that sought to develop them. The spying operation later became public after former Asis officer Witness K approached lawyer and former ACT attorney general Bernard Collaery in 2013. Collaery also represented Timor-Leste. Their efforts to assist its challenge to the maritime boundary agreement at The Hague were followed by a raid on Collaery’s office and the seizure of Witness K’s passport.

Timor-Leste withdrew its espionage claims in 2017 as a confidence-building step, and a new maritime border agreement followed in 2018. In a 2019 affidavit in proceedings against Collaery, Timor-Leste president Jose Ramos-Horta said fuller disclosure would benefit relations with Australia rather than harm them. The proceedings against Collaery were dropped in 2022.