AFP - Senior Australian politicians insisted Thursday the country's sports minister was not a "spy" for Washington after WikiLeaks cables reportedly revealed he was a "protected" source for the United States.

Mark Arbib, a key figure in June's overthrow of former leader Kevin Rudd, was a valued contact in Canberra and met US diplomats "repeatedly" according to WikiLeaks memos published exclusively by the Sydney Morning Herald.

Arbib issued a statement saying he was "publicly known as a strong supporter of Australia's relationship with the United States."

"I, like many members of the federal parliament, have regular discussions about the state of Australian and US politics with members of the US mission and consulate," he added.

Elevated from minor portfolios to the Sports Ministry following Australia's August elections, Arbib was described as a "right-wing powerbroker and political rising star" who was influential in Rudd's inner circle.

He kept US officials briefed on the inner workings of Australia's government and ruling Labor party, according to the Herald report, including candid commentary ahead of Rudd's overthrow by his deputy, Julia Gillard.

"(Rudd wants) to ensure that there are viable alternatives to Gillard within the Labor party to forestall a challenge," Arbib reportedly told US diplomats, some eight months before the coup.

Senior politicians were quick to defend Arbib, including fellow coup architect Bill Shorten, now the assistant treasurer.

"I completely reject the idea that he is a spy, I just think that's nonsense," Shorten told Sky News.

"I think that the commentary I've seen this morning in the newspapers is dinner party gossip masquerading as US intelligence... Each week someone's got to send a report off to America, so they jot down gossip and conversation," he added.

Health Minister Nicola Roxon said there was "nothing extraordinary about people meeting and talking with diplomats" and urged against reading "anything at all sinister into that".

The Herald said WikiLeaks cables also showed that the US took a keen interest in the rise of Gillard, now Australia's Prime Minister, and saw her as the "front-runner" to replace Rudd as early as June 2008.

"Many (party) figures" offered assurances of her pragmatism, according to the leaked memos, assuaging US concerns that she was ambivalent about Australia's alliance with Washington.

"Labor party officials have told us that one lesson Gillard took from the 2004 elections was that Australians will not elect a PM who is perceived to be anti-American," one cable reportedly read.

Rudd, now Australia's foreign minister, was himself the subject of an embarrassing cable published earlier this week in which he urged the US to use force against key trading partner China if "everything goes wrong".

Other diplomatic memos obtained from WikiLeaks by the Sydney Morning Herald described the foreign minister as a "mistake-prone control freak" who made hasty decisions and had micro-managing tendencies.

Mandarin-speaking former diplomat Rudd, known as a workaholic, shrugged off the stinging diplomatic criticism from his country's most important partner, saying it was "water off a duck's back".

"I'm sure much worse has been written about me in the past and probably much worse will be written about me in the future but frankly, mate, I don't care," Rudd said.

Gillard has slammed WikiLeaks, founded by Australian-born hacker Julian Assange, as irresponsible and illegal, and Attorney-General Robert McClelland Thursday said the obtaining and distribution of the classified files "may well be an offence".

"To release that sort of information by an officer of the Commonwealth, if it were Australian material, would in my view certainly involve criminality," McClelland said.

Rudd says US diplomatic security is at fault, not the whistleblowing site.