WikiLeaks founder Julian Assange faces arrest for breaching his bail conditions and spending the night in the Ecuadorian embassy in London, police said.
His bail conditions included staying at a given address between 10pm and 8am every night.
Police said he broke the terms of his bail by seeking political asylum inside the Ecuadorian embassy in Knightsbridge citing the UN Declaration of Human Rights.
Ecuador's foreign minister confirmed Assange's request and said the government in Quito was analysing the situation.
Police are stationed outside the embassy but are powerless to act against Assange unless he leaves the building. The embassy is outside the jurisdiction of British law under international diplomatic protocol.
The Foreign Office said that as long as Assange remains inside, he is "beyond the reach of police".
Police said Assange had violated the terms of his bail, which include an overnight curfew, and "is now subject to arrest under the Bail Act".
Assange wrote to Rafael Correa, the Ecuadorian president and alleged to be a big fan of WikiLeaks, saying he was being persecuted and could not return to his home country of Australia.
The WikiLeaks founder is facing extradition charges to Sweden after the supreme court refuses to take up his appeal case. Sweden wants him for questioning over rape and sexual assault allegations. Assange denies any wrongdoing.
He fears that if he is sent to Sweden it may lead to him being sent to the US to face charges over WikiLeaks, who published thousands of leaked diplomatic cables.