WASHINGTON, March 19 (Reuters) - WikiLeaks founder Julian Assange is likely to remain at the Ecuadorean Embassy in London where he has taken refuge as long as U.S. authorities pursue a criminal investigation of his anti-secrecy group, one of his lawyers said.
Speculation rose that he might leave the embassy after Swedish authorities last week offered to question him there over allegations of sexual misconduct, dropping their insistence that he go to Stockholm for questioning about a 2010 incident.
He refused to return to Sweden, arguing that the Swedes would send him on to the United States to face possible trial. Assange, 43, denies the allegations, which are not related to WikiLeaks' publication of U.S. military and diplomatic documents five years ago.
Michael Ratner, a U.S. lawyer who represents Assange and WikiLeaks, said if Assange left the embassy, where he has been holed up for just over 1,000 days, he was likely to be arrested by British authorities and risked being extradited to America.
"Even were the Swedish case to be disposed of, the U.K. would arrest Assange upon leaving the embassy for claimed violations of bail conditions or something similar," Ratner told Reuters. Washington would almost certainly seek his extradition, he said.
Ratner said a recent federal court ruling disclosed that the FBI and U.S. Justice Department were conducting a "multi-subject investigation" of WikiLeaks and he said it had been going on for "at least five years."
Another legal source close to Assange said he would remain in the Ecuadorean Embassy until the U.S. ended a grand jury investigation of WikiLeaks.
Joshua Stueve, a spokesman for the U.S. Attorney's office in Alexandria, Virginia, said the investigation into WikiLeaks remained open. Other U.S. law enforcement sources said criminal charges had not yet been filed against Assange.
The sex allegations against Assange, who is an Australian, were lodged against him by two female WikiLeaks supporters who hosted him during a visit to Sweden.
British authorities have declined to say what they might do if Sweden were to close its investigation of Assange and he were to try to leave the Ecuadorean Embassy in London. (Reporting By Mark Hosenball; Editing by David Storey and Alan Crosby)