WikiLeaks founder Julian Assange will leave the Ecuadorian embassy in London, where he took refuge in June 2012 to avoid extradition to Sweden, and accept arrest on Friday if a UN panel investigating his case rules against him, he said in a statement.
Assange, 44, is wanted in Sweden for questioning over allegations of rape in 2010 which the Australian denies.
"Should the UN announce tomorrow that I have lost my case against the UK and Sweden, I shall exit the embassy at noon on Friday to accept arrest by British police as there is no meaningful prospect of further appeal," Assange said in the statement posted on the Wikileaks Twitter account.
"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."
Assange fears Sweden will extradite him to the US, where he could be put on trial over WikiLeaks' publication of classified military and diplomatic documents, one of the largest information leaks in US history.
The UN Working Group on Arbitrary Detention is currently considering a request for relief by Assange, who argued in a submission that his time in the embassy constituted arbitrary detention.
Assange argued that he had been deprived of his fundamental liberties, including lack of access to sunlight or fresh air, adequate medical facilities, as well as legal and procedural insecurity.
A spokesman for Assange could not immediately be reached for comment.