UN human rights experts have again demanded the UK abide by its international obligations and allow Julian Assange to walk free from the Ecuadorian embassy in London.

The WikiLeaks founder has been living inside the embassy for more than six years, fearing he will be extradited to the US if he leaves.

The United Nations Working Group on Arbitrary Detention, which has previously concluded Assange is being arbitrarily deprived of his freedom, urged the UK government to "honour its obligations".

The group said investigations by Swedish authorities ended more than 18 months ago, and the only ground remaining for Assange's continued deprivation of liberty is a bail violation in the UK.

That was a minor offence that cannot justify years of confinement, the group said.

"Mr Assange should be able to exercise his right to freedom of movement in an unhindered manner, in accordance with the human rights conventions the UK has ratified," it said in a statement from Geneva.

The group expressed concerns about the effect on Assange's health and said the UK has a responsibility to honour its commitment to the International Covenant on Civil and Political Rights.

"It is time that Mr Assange, who has already paid a high price for peacefully exercising his rights to freedom of opinion, expression and information... recovers his freedom," the group said.

Mr Assange's father John Shipton visited the embassy on Friday, and said it was time for "this torment to end", reports the Sydney Morning Herald.

"His health is declining after years of ongoing stress, no sunlight and restricted access to visitors."

PA / Newshub.