Wikileaks founder Julian Assange has been served with an extradition notice by the Metropolitan Police.
Officers from the extradition unit delivered a note to Mr Assange at Ecuador's London embassy.
Mr Assange took refuge there last week and is seeking diplomatic asylum to prevent being sent to Sweden where he is accused of rape and assault.
Scotland Yard said the notice required a 40-year-old man to attend a police station "at a time of our choosing".
The Wikileaks website published a mass of leaked diplomatic cables that embarrassed several governments and international businesses.
Mr Assange fears that if he is sent to Sweden he could be sent on to the United States to face charges over Wikileaks and that he could face the death penalty.
In a brief statement to the BBC, Scotland Yard said: "This is standard procedure in extradition cases and is the first step in the removal process.
"He remains in breach of his bail conditions and failure to surrender would be a further breach of those conditions and he is liable to arrest."
Under international diplomatic arrangements, the Metropolitan Police cannot go into the embassy to arrest Mr Assange.
Mr Assange, whose bail conditions include staying at a named address between 22:00 and 08:00 BST, arrived at the embassy in Knightsbridge on Tuesday last week
Ecuador is considering Mr Assange's application for asylum.