A lawyer for Julian Assange has urged the United Nations to make an official visit to see the impact on the WikiLeaks founder of living inside the Ecuadorian embassy for the past six years.

Jennifer Robinson told the UN Human Rights Council in Geneva that Mr Assange was unable to obtain proper medical attention and was being denied sunlight or outdoor access.

A vigil will be held outside the embassy in London on Tuesday evening, six years to the day since he arrived, later to be granted political asylum.

Ms Robinson told the UN that the British authorities had made it clear that if Mr Assange leaves the embassy to seek medical treatment he will be arrested.

The US administration has said that prosecuting him is a “priority”, said Ms Robinson.

“He cannot leave the embassy because the UK will not provide assurances against extradition to the US.

“The UK is showing deliberate disregard for his medical needs,” she said, adding that the UN should send a special rapporteur to visit the embassy.

His confinement in the embassy is having a “severe impact” on his physical and mental health, she said.

He was being asked to choose between his human right to asylum and his human right to medical treatment, said Ms Robinson, adding: “No-one should have to make that choice.”

She reminded the council that in 2016 the United Nations Working Group on Arbitrary Detention said that Mr Assange was being arbitrarily detained.

It called on the Swedish and British authorities to end his “deprivation of liberty, respect his physical integrity and freedom of movement, and afford him the right to compensation”.

Mr Assange’s internet access was cut off in March and restrictions were placed on who can visit him after he tweeted his support for separatist movements in Catalonia in Spain.

Ms Robinson visited him earlier this month, with officials from the Australian High Commission in London.