By Niklas Pollard and Anna Ringstrom
STOCKHOLM (Reuters) - Sweden reopened an investigation into a rape allegation against WikiLeaks founder Julian Assange on Monday and will seek to extradite him from Britain, a potential setback to efforts by the United States to put him on trial over a huge release of secret documents.
Deputy Chief Prosecutor Eva-Marie Persson told a news conference in Stockholm she would continue a preliminary investigation that was dropped in 2017 without charges being brought after Assange took refuge in the Ecuadorean embassy in London.
Assange, who denies the accusation, was arrested in Britain last month after spending seven years hiding inside the embassy.
The Swedish prosecutor said she would request Assange be detained in his absence on probable cause for an allegation of rape and that her office would issue a European arrest warrant - the start of the extradition process.
The United States is also seeking to extradite him on conspiracy charges relating to the public release by Wikileaks of a cache of secret documents, including assessments of foreign leaders, wars and security matters.
The British courts will have to rule on the two extradition requests, with Home Secretary Sajid Javid having the final say on which one takes precedence.
"I am well aware of the fact that an extradition process is ongoing in the UK and that he could be extradited to the US," Persson said.
The 47-year-old Assange is currently in a London prison serving 50 weeks behind bars for jumping bail when he fled to the Ecuadorean embassy in 2012.
A British judge has given the U.S. government a deadline of June 12 to outline its case against Assange.
The statute of limitation for rape in Sweden is 10 years - a deadline which would be reached in mid-August next year for that alleged incident, leaving prosecutors pressed for time should they decide to file any formal charge.
"Everything depends on how this will be handled by the British authorities and courts," said Mark Klamberg, a professor of international law at Stockholm University.
"There is a possibility, or risk depending on how you see it, that this is going to take a long time," he said.
If Assange was taken to the United Sattes, this would likely rule out his facing trial in Sweden due to the statute of limitation.
Persson said she would request to interview Assange while he was in British custody, but that this would require the consent of the Australian, who fought unsuccesfully through the British courts to avoid extradition before fleeing to the embassy.
A lawyer representing the victim in the rape investigation urged Swedish prosecutors to move quickly.
"We are not going to give up until a charge is brought and the case goes to court," lawyer Elisabeth Massi Fritz told a news conference.
"My client feels great gratitude and she is very hopeful of getting restitution and we both hope that justice will win."
Assange's supporters cast him as a dissident facing the wrath of a superpower over one of the largest compromises of classified information in U.S. history.
Wikileaks said the reopening of the Swedish investigation would give Assange a chance to clear his name.
"Since Julian Assange was arrested on 11 April 2019, there has been considerable political pressure on Sweden to reopen their investigation, but there has always been political pressure surrounding this case," Kristinn Hrafnsson, WikiLeaks' editor-in-chief, said in a statement.
If convicted in Sweden, Assange could face a prison sentence of up to four years.
"His attitude is that he is happy to cooperate with Sweden and that he wants to be interviewed and that he wants to clear his name," Per Samuelson, a Swedish lawyer for Assange, told Reuters.
"How that will happen now, I don't know. He has his hands full with, for him, much more important issues, namely avoiding being extradited to the U.S."
Nick Vamos, lawyer at London-based firm Peters & Peters and former head of extradition at Britain's Crown Prosecution Service, told Reuters before Monday's decision that he expected a Swedish request would take supremacy.
"In the event of a conflict between a European Arrest Warrant and a request for extradition from the US, UK authorities will decide on the order of priority," a Swedish prosecutor's statement said.
WikiLeaks published hundreds of thousands of secret U.S. diplomatic cables that laid bare often critical U.S. appraisals of world leaders, from Russian President Vladimir Putin to members of the Saudi royal family.
It also published a classified U.S. military video showing a 2007 attack by Apache helicopters in Baghdad that killed a dozen people, including two Reuters news staff.
(Additional reporting by Simon Johnson, Johan Ahlander and Helena Soderpalm in Stockholm, and Guy Faulconbridge in London; Editing by Angus MacSwan)