Australia and the United States mounted a joint surveillance operation on Indonesia during 2007 UN climate talks in Bali, a report said Sunday in revelations likely to exacerbate strained ties with Jakarta.
The Guardian newspaper's Australian edition cited a document from US whistleblower Edward Snowden showing Australian spy agency the Defence Signals Directorate worked alongside America's National Security Agency (NSA) to collect the phone numbers of Indonesian security officials.
Australia's relationship with close neighbour Indonesia is already under pressure after reports last week that Canberra's overseas diplomatic posts were involved in a vast US-led surveillance network.
Missions in Indonesia, as well as embassies or consulates in China, were reportedly used to monitor phone calls and collect data, sparking demands for an explanation from Jakarta and Beijing.
The Guardian said the 2007 operation at the United Nations climate change conference was not particularly successful, with the only tangible outcome being the mobile phone number of Bali's chief of police.
"The goal of the development effort was to gain a solid understanding of the network structure should collection be required in the event of an emergency," according to an account of the mission included in a 2008 weekly report from the NSA base at Pine Gap in Australia, one of the agency's biggest overseas bases.
Summing up at the end of the operation, the NSA, according to the Guardian, said: "Highlights include the compromise of the mobile phone number for Bali's chief of police.
"Site efforts revealed previously unknown Indonesian communications networks and postured us to increase collection in the event of a crisis."
While largely unsuccessful, the operation is hugely embarrassing for Australia.
At the time, Kevin Rudd was the country's newly elected prime minister and he attended the summit -- his first high-profile international foray -- at the personal invitation of Indonesian President Susilo Bambang Yudhoyono.
Both leaders agreed then to work together to advance ties.
The latest allegations are another blow to ties between the two countries, which have been tested by new Prime Minister Tony Abbott's hardline policies on trying to stop asylum-seekers who board boats in Indonesia from arriving in Australia.
Last week Abbott said of the spy network reports: "Every Australian governmental agency, every Australian official, at home and abroad, operates in accordance with the law and that's the assurance that I can give people at home and abroad."
The Department of Foreign Affairs and Trade would not comment on the latest revelation.
"As a matter of principle and long-standing practice, the Australian government does not comment on intelligence matters," a spokeswoman told AFP.
Widespread reports of NSA spying based on leaks from fugitive intelligence analyst Snowden, including that the agency was monitoring German Chancellor Angela Merkel's phone, have already sparked a major trans-Atlantic rift.
After last week's claims in the Sydney Morning Herald, which amplified earlier revelations by German magazine Der Spiegel, China's foreign ministry demanded the Australian side "make a clarification".
Jakarta summoned Australian ambassador Greg Moriarty for an explanation on Friday while Indonesian Foreign Minister Marty Natalegawa described the reported spying activities as "just not cricket", saying his government was "obviously deeply concerned".