Australia's foreign minister said the US government and whoever originally leaked 250,000 diplomatic cables should bear the responsibility for any security breaches – not the Australian WikiLeaks founder, Julian Assange.

Kevin Rudd said legal liability rested with the initial leakers and Assange should be protected from threats to his safety as the US stepped up pressure on companies and organisations with ties to WikiLeaks.

His comments came after the Sydney Morning Herald published leaked cables in which US diplomats described Rudd, then Australia's prime minister, as a mistake-prone control freak with a tendency towards making "snap announcements without consulting other countries or within the Australian government". Rudd dismissed the criticism, saying that it was "like water off a duck's back".

Assange, who was arrested in London yesterday, faces extradition to Sweden for alleged sexual assaults, but Rudd took the offensive against the US over the leaks. "Mr Assange is not himself responsible for the unauthorised release of 250,000 documents from the US diplomatic communications network," Rudd told Reuters.

"The Americans are responsible for that. I think there are real questions to be asked about the adequacy of their security systems and the level of access that people have had to that material over a long period of time.".

"The core responsibility, and therefore legal liability, goes to those individuals responsible for that initial unauthorised release," he said.

"There is a separate and secondary legal question … which is the legal liabilities of those responsible for the dissemination of that information, whether it's WikiLeaks, whether it's Reuters, or whether it is anybody else.".

His robust remarks in interviews with the Reuters news agency and Seven network coincided with the publication of an opinion piece by Assange in the Australian in which the WikiLeaks founder accused Australian authorities of "pandering" to the US and being prepared to harass WikiLeaks supporters and "frame" an Australian citizen.

Rudd said today that Australia would provide Assange with consular assistance after a request by him to the country's high commission in London. "That is the proper thing to do for any Australian citizen," he said.

Julia Gillard, who toppled Rudd in June, yesterday called WikiLeaks actions "grossly irresponsible" but said publication would not have been possible "if there had not been an illegal act undertaken" in the US. However, she made clear Australian authorities were still investigating whether Assange had broken any Australian laws.

Assange says he has faced calls for his assassination, among other threats. Rudd said: "We'd be concerned about the safety and security of all Australians. People should be free from any such threats."

Asked what governments should do in response to the leaked cables, Rudd said: "Rule No 1 for our friends in the United States is – how do you tighten things up a bit?

"I think that's a fair old question. Maybe 2 million or so people having access to this stuff is a bit of a problem.''

According to the Sydney Morning Herald, the leaked cables show how US diplomats initially saw Rudd as a "safe pair of hands", but the favourable impression was soon replaced by criticism of his apparent focus on media opportunities and a string of "foreign policy mistakes".

Rudd dismissed the criticism of his own "micro-management" in leaked cables, saying: "I don't, frankly, give a damn about this sort of thing. You just get on with it."

Gillard defended Rudd, telling reporters today: "Kevin Rudd is a man who throughout his adult life has devoted himself to expertise in foreign policy. He's bringing that expertise to bear for the Australian nation and doing an absolutely first-class job."