Foreign Minister Julie Bishop will seek advice on the case of WikiLeaks founder Julian Assange after a UN panel reportedly ruled he's been "arbitrarily detained" in an embassy in London.

But she says Mr Assange has not sought Australian government assistance for years despite there being a standing offer to him to take it up.

The 44-year-old Australian has been in the Ecuadorian embassy since 2012 after seeking asylum there in a bid to avoid extradition to Sweden where he faces an allegation of rape.

He's also concerned Sweden will extradite him to the US where he could be put on trial over WikiLeaks' publication of top secret military and diplomatic cables in 2010.

The UN Working Group on Arbitrary Detention is due to release its report on Mr Assange on Friday but on Thursday Sweden's foreign ministry said the panel had ruled in his favour.

"Their working group has made the judgment that Assange has been arbitrarily detained in contravention of international commitments," a spokeswoman for the ministry said.

But the Metropolitan Police in London said on Thursday that Mr Assange would face arrest if he tried to leave the embassy.

Ms Bishop told reporters in London she was not sure if the UN report would change Mr Assange's circumstances but she would certainly be reading it and seeking advice.

"Mr Assange has not sought consular assistance from Australia for some years now and there has been a standing offer to him.

"So until such time as he seeks further consular assistance I'll keep a watching brief on the matter," Ms Bishop said.

"I understand that the British government maintains that it makes no difference to the situation as it currently stands, whatever the report says, and it's not a binding report."

Ms Bishop said if Mr Assange sought support from the Australian government the appropriate consular assistance would be provided.

"I will ascertain what Australia's obligations are."