The mother of WikiLeaks founder Julian Assange has released an open letter to Foreign Affairs Minister Kevin Rudd demanding he take up her son's case or resign.

Swedish authorities are trying to extradite Mr Assange from the United Kingdom so he can be interviewed over complaints of sexual misconduct.

Christine Assange read from the letter outside Mr Rudd's parliamentary office in Brisbane last night.

She demanded he make strong and urgent representations to Sweden to drop the extradition attempt, saying it violates international standards of fairness.

"If you do not act I can only conclude one of two possibilities - that you have been gagged or intimidated, possibly by the very person who deposed you from your prime ministership eight months ago," she said.

"Alternatively you have not been gagged or intimidated but are choosing freely to be derelict from your duties as Australian Foreign Minister."

She says she wants Mr Rudd to explain why he is not acting to protect her son's consular and legal rights, as he has previously promised to do.

"Julian did not even get the laptop you had publicly promised him which he needed to prepare for his case while he was in Wandsworth Prison," she said.

"As far as I am aware you have made no diplomatic protest to Sweden for their abuse of my son's legal and human rights, nor have you protested to the US for their incitements to kidnap and murder."

Christine Assange also dismissed the newly released book Inside WikiLeaks by Daniel Domscheit-Berg, a former employee of the whistleblowing site, saying "there's a lot of money to be made out of Julian at the moment".

Last week Julian Assange urged Prime Minister Julia Gillard to try to bring him back to Australia, condemning Canberra's "diplomatic silence".

"There has been outrageous and illegal calls to have me and my staff killed, clear cases of incitement to violence. Yet the Australian government has condoned this behaviour by its diplomatic silence," he said, in a video posted on the Sydney Morning Herald website.

"Julia Gillard should be taking active steps to bring me home and to protect our people. She should be contacting the US embassy and demanding that it back off."

- ABC/AFP