Vigils were held in several countries on Tuesday to mark the sixth anniversary of Julian Assange living inside the Ecuadorian embassy in London.
Scores of people stood outside the building, with many giving speeches in support of the Australian-born WikiLeaks founder.
Among those taking part was Susan Manning, mother of Chelsea, who was jailed in the United States for leaking military information.
Mr Assange remained hidden from view inside the embassy, where he has been denied access to the internet or visitors for weeks.
Vigils were also held in several cities across the United States, New Zealand, India, Sri Lanka and Ireland.
One of Mr Assange's lawyers has urged the United Nations to make an official visit to see the impact on him of living inside the embassy for the past six years.
Jennifer Robinson told the UN Human Rights Council in Geneva on Monday that Mr Assange was unable to obtain proper medical attention and was being denied sunlight or outdoor access.
Ms Robinson told the UN that the British authorities had made it clear that if Mr Assange left the embassy to seek medical treatment he would 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 was 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.
Australian Associated Press