According to Press TV, the UN working group, which has been considering a request by Assange for a ruling, is due to publicize the findings of its investigation into his appeal on Friday.
The British broadcaster the BBC, however, said Thursday the panel had ruled that Assange, currently holed up in Ecuador's embassy in London, was "arbitrarily detained.”
UK police said Assange will still be arrested if he leaves the building where he took refuge in June 2012 to avoid extradition to Sweden over rape and sexual assault allegations.
Earlier on Thursday, Assange posted a statement on the WikiLeaks Twitter account, saying he will hand himself over to the British police if the United Nations rules against him.
"Should the UN announce tomorrow that I have lost my case against the United Kingdom and Sweden, I shall exit the [Ecuadoran] embassy at noon on Friday to accept arrest by British police as there is no meaningful prospect of further appeal.
"However, should I prevail and the state parties be found to have acted unlawfully, I expect the immediate return of my passport and the termination of further attempts to arrest me," he added.
Assange filed a complaint in 2014 with the UN, saying he was being "arbitrarily detained" as he could not leave the embassy.
In the appeal, he said the confinement has deprived him of access to fresh air or sunlight and adequate medical care. He said he is subject to round-the-clock surveillance and remains in a constant state of insecurity.
The panel has taken evidence from the UK and Sweden. Its ruling, however, will not have any formal influence with the British and Swedish authorities.