WikiLeaks' founder Julian Assange should be sent to Sweden from Britain to face questioning over alleged sex crimes, London's High Court ruled on Wednesday, rejecting his appeal against extradition.
Swedish authorities want to question the 40-year-old over accusations of rape and sexual assault made by two female former WikiLeaks volunteers.
Assange now has two weeks to make a final appeal to the Supreme Court.
However, any appeal to Britain's highest judicial body must be made on a point of law considered to be of general public interest.
Permission to appeal must also be obtained first from the High Court.
Wearing a navy blue suit and sporting a Remembrance Day poppy in his lapel, Assange was mobbed by supporters as he arrived at court on Wednesday.
He listened intently during the 10-minute hearing but showed no emotion as the result was read out.
He was hugged and kissed by a female supporter after the hearing while outside banners fixed to the court railings proclaimed him to be a "casualty of war and truth".
Assange himself made no immediate comment afterwards but from Sweden, his lawyer Bjorn Hurtig, told Reuters by phone: "This was not entirely unexpected."
If Assange decides not to appeal he will be transferred to Sweden within two weeks, Hurtig said.
"He would then be brought before a judge to see if he is to be detained, and the investigation will proceed," he added.
A lawyer for the women in Sweden making the allegations criticised the High Court for having taken some four months to reach its verdict.
"This decision was exactly what I expected, but I am very critical about the fact that it has taken the High Court such long time, from July," said Claes Borgstrom.
Assange was arrested in Britain 11 months ago and has since been living under strict bail conditions at the country estate of a wealthy supporter.
His whistle-blowing website caused a stir last year by publishing thousands of secret US diplomatic cables.
In 2010 it posted 391,832 secret documents on the Iraqi war and 77,000 classified Pentagon documents on the Afghan conflict.
It also made available about 250,000 individual cables -- the daily traffic between the State Department and more than 270 American diplomatic outposts around the world.
A British judge first approved the Swedish request for the computer expert's extradition in February.
Assange's lawyers have argued the Swedish demand is legally flawed and that the sex was consensual. Assange has also accused the United States of putting pressure on Britain, Sweden and the media.
Last month, Assange, an Australian citizen, said WikiLeaks would stop publishing secret cables and devote itself instead to fund-raising because of a financial block on payments to the site by U.S. firms such as Visa and MasterCard.
He said if the block was not ended by the turn of the year, WikiLeaks would not be able to continue.