Opposition Leader Peter Dutton may have jeopardised multi-billion-dollar submarine plans by divulging sensitive discussions with the United States, insiders say. 

Former defence minister and now Opposition Leader Peter Dutton wrote in an opinion piece for The Australian newspaper this week that he was confident of securing two American Virginia-class nuclear submarines by 2030.

Australia, the United Kingdom and the United States are working on plans for a fleet of nuclear-powered submarines to replace Australia’s ageing Collins-class vessels as part of the AUKUS partnership.

Mr Dutton claimed that if the Coalition had remained in office it would be “in a position to make an announcement around July-August” about the new subs, and that Labor is contemplating building more conventionally powered submarines instead.

“I really worry that Labor is now walking away from AUKUS, from the submarine deal, and that is clearly not in our national interest,” Mr Dutton said. 

Government and industry insiders have told reporters they were alarmed at Mr Dutton's disclosure of defence advice, including his fear that the Collins-class “diesel-electric submarines would not be able to compete against the Chinese in the South China Sea beyond 2035”.

Mr Dutton's editorial has “buggered” plans for a joint announcement by the end of the year, one insider told the ABC. 

Dr Peter Dean, chair of defence studies at the University of Western Australia, said Mr Dutton’s comments were certainly concerning.

“I'm sure that the UK wouldn't be happy to learn from a newspaper article that, potentially, their submarine is not an option and I'm sure there's plenty of people in the US Congress, the Pentagon and other parts of the US who were very interested to read these possible developments,” Dr Dean said.

“These are sensitive negotiations and I think the great concern here is that Peter Dutton has basically worked against the national interest in an attempt for some domestic political point-scoring.”

Defence Minister and Deputy Prime Minister Richard Marles slammed his predecessor's “loose” comments, saying they undermined the tripartite AUKUS security agreement. 

“This is rank politics and is completely inconsistent with everything Peter Dutton was doing and saying in government,” Mr Marles said.

“This outburst today, from someone so recently in the chair, is damaging to Australia's national interest. The comments are loose and undermine the AUKUS agreement.

“The government has made no decision on the preferred submarine. All options remain on the table.

“The Coalition's ability to talk tough and beat their chest without delivering is only being highlighted whilst they're in Opposition.”