British Foreign Secretary Philip Hammond has branded a United Nations working group report on the "arbitrary detention" of WikiLeaks founder Julian Assange as "frankly ridiculous".
Speaking at a joint press conference with his Iranian counterpart in London, Mr Hammond said Mr Assange was in fact "hiding from justice".
He spoke out after the UN working group ruled Mr Assange was being "arbitrarily detained" in the Ecuadorian embassy in London - and called for him to be paid compensation.
The UN Working Group on Arbitrary Detention said the Swedish and British authorities should end Assange's "deprivation of liberty" and respect his physical integrity and freedom of movement.
Assange is wanted for questioning over an alleged sex offence in Sweden but has avoided extradition by seeking refuge in the embassy, where he has been living for more than three years after being granted political asylum by the Ecuadorian government.
He claims he will be transported to the United States to be quizzed over the activities of WikiLeaks if he is extradited to Sweden. There is an espionage case against him in the US.
He filed a complaint against Sweden and the UK to the UN Working Group on Arbitrary Detention in September 2014.
But Hammond said: "I reject the decision of this working group. It is a group made up of lay people and not lawyers.
"Julian Assange is a fugitive from justice. He is hiding from justice in the Ecuadorian embassy.
"He can come out any time he chooses ... But he will have to face justice in Sweden if he chooses to do so.
"This is frankly a ridiculous finding by the working group and we reject it."
In a strongly worded letter to the UN Working Group, Julian Braithwaite, UK Permanent Representative to the UN, expressed "serious doubts about the legal arguments" put forward.
"The majority opinion claims that Mr Assange's imprisonment immediately following his arrest under the European Arrest Warrant constituted detention 'outside the cloak of legal protection'. There is no basis, in law or fact, for this finding, as the UK will be setting out in our formal response," he wrote.
"The majority opinion of the Working Group further refers to Mr Assange being held under 'house arrest' for a period of 550 days. Yet Mr Assange was released on conditional bail, which was an alternative to being remanded in custody, by the UK authorities."
He went on to claim Mr Assange was free to leave the embassy of Ecuador at any point: "There is no basis for the majority opinion to assert that his decision to remain constitutes detention by the United Kingdom."
A spokesman for British Prime Minister David Cameron said: "It's ridiculous. There's a European arrest warrant out for him. He has never been arbitrarily detained in this country.
"It's entirely his choice to remain in the Ecuadorian embassy and he is avoiding lawful arrest by choosing to remain there."
