Julian Assange, the WikiLeaks chief, has taken refuge in Ecuador's embassy in London and is seeking political asylum in the South American country.
Tuesday's development comes less than a week after Britain's supreme court rejected Assange's bid to reopen his extradition case.
Assange is wanted for questioning in Sweden after two women accused him of sexual misconduct during a visit to the country in mid-2010. He denies the allegations.
"I can confirm that today I arrived at the Ecuadorian embassy and sought diplomatic sanctuary and political asylum," Assange said in a statement on Tuesday.
"This application has been passed to the Ministry of Foreign Affairs in the capital Quito.
"I am grateful to the Ecuadorian ambassador and the government of Ecuador for considering my application," he added.
Assange's legal struggle to stay in Britain has dragged on for the better part of two years, clouding his website's work exposing secrets.
Ricardo Patino, Ecuador's foreign minister, announced that Assange had written to Rafael Correa, Ecuador's leftist president, saying he was being persecuted and seeking asylum.
He said that Assange, who is Australian, had argued that "the authorities in his country will not defend his minimum guarantees in front of any government or ignore the obligation to protect a politically persecuted citizen".
Patino said Assange had said it was impossible for him to return to his homeland because it would not protect him from being extradited to "a foreign country that applies the death penalty for the crime of espionage and sedition".
The reference is presumably to the US. Assange claims the US has secretly indicted him for divulging American secrets and will act on the indictment if Sweden succeeds in extraditing him from Britain.
'Obligation to review all applications'
In a statement, Ecuador's embassy in London: said "This afternoon Mr Julian Assange arrived at the Ecuadorian Embassy seeking political asylum from the Ecuadorian government.
"As a signatory to the United Nations Universal Declaration for Human Rights, with an obligation to review all applications for asylum, we have immediately passed his application on to the relevant department in Quito.
"While the department assesses Mr Assange’s application, Mr Assange will remain at the embassy, under the protection of the Ecuadorian Government.
"The decision to consider Mr Assange’s application for protective asylum should in no way be interpreted as the Government of Ecuador interfering in the judicial processes of either the United Kingdom or Sweden."
Assange shot to international prominence in 2010 with the release of hundreds of thousands of secret US documents, including a hard-to-watch video that showed US forces gunning down a crowd of Iraqi civilians and journalists whom they had mistaken for fighters.
Australian authorities have co-operated with the US in investigating WikiLeaks' conduct.
The Australians have concluded that Assange has broken no Australian law.