Julian Assange’s legal team says Britain’s international reputation is at risk if the country ignores the findings of a United Nations panel which is expected to rule that the Australian WikiLeaks founder has been “arbitrarily detained”.

Mr Assange has been holed up in the Ecuadorian embassy in London since seeking asylum in June 2012, after an arrest warrant was issued over sexual assault allegations in Sweden.

British police have been stationed outside the embassy for the last three-and-a-half years and said they would arrest the Australian if he tried to leave.

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The Swedish Foreign Ministry and the BBC both reported that the UN panel would rule in Mr Assange’s favour when it handed down its ruling — which has no real legal standing — later tonight.

Mr Assange’s lawyer Jennifer Robinson said in recent years Iran, Myanmar and the Maldives had followed the directions of the panel.

She said the British government would risk its international reputation if it ignored this ruling.

“The UK has already put out a statement saying that they will enforce the extradition agreement, so he may well still face arrest,” Ms Robinson said.

“If the UN calls for his immediate release, there will need to be some sort of negotiation to ensure that his rights are protected.

“So I suspect he will not leave the embassy unless we get an assurance that his right to asylum will be protected and unless and until we get that assurance, he will need to remain inside the embassy.

“What we see with other decisions, if you look at the former president of the Maldives, it took months after the decision to negotiate his release and I suspect there will be some lag time in this circumstance as well.

“But as I said, if this decision is positive, we certainly hope and expect that the UK and Sweden will respect it and that we’ll finally get a resolution to this case.”

Another member of the legal team, Per Samuelson, said the ruling in Mr Assange’s favour should prompt immediate action.

“I see no other way out of this for Sweden and the prosecutor but to cancel the decision to detain Julian Assange in absentia and to close the case, drop the suspicions against him and close the pre-investigation,” Mr Samuelson said.

“It’s over, in my firm opinion.”

Decision has ‘no formal impact on rape investigation’

Police monitor supporters of Assange in London. Photo: Reuters

The British government said it remained obliged to arrest Mr Assange and extradite him to Sweden if he left the embassy.

A government spokesperson said authorities had been “consistently clear that Mr Assange has never been arbitrarily detained by the UK, but is, in fact, voluntarily avoiding lawful arrest by choosing to remain in the Ecuadorean embassy”.

“An allegation of rape is still outstanding and a European Arrest Warrant in place, so the UK continues to have a legal obligation to extradite Mr Assange to Sweden,” they added.

Swedish prosecutors previously said the UN decision would have no formal impact on their rape investigation under Swedish law.

Australian Foreign Minister Julie Bishop said the Government had not been contacted by Mr Assange in years, and until he called them they could not get involved in the matter.

‘He was hopeful, it was his last chance’

Assange announced his decision via Twitter. Photo: Twitter

Vaughan Smith, founder of the Frontline journalism club and a key supporter of the Wikileaks founder, said Mr Assange was desperate to resolve the matter.

Mr Assange has always argued the real threat to him is the United States, which he claims wants to extradite him to face charges over the release of millions of top secret documents through WikiLeaks.

Mr Assange indicated he would hand himself over to police if the ruling went against him.

Mr Smith said he had spoken to Mr Assange, who had not been clear about what the next step would be for him after the ruling.

“He was hopeful, it was his last chance,” Mr Smith said.

“But I must say I was impressed because he very much said ‘Look, I would have exhausted all legal recourse, of course I’m innocent but there’s nowhere else I can go, I’ll hand myself in if it goes against me.'”

Swedish prosecutors have been waiting for permission from the Ecuadorians to interview Mr Assange in the London embassy.

The lesser charges of sexual assault were dropped because of time limits, but Swedish prosecutors said the decision would have no formal impact on their rape investigation.

– with Lisa Millar