LONDON — Julian Assange, the founder of WikiLeaks, must remain in prison until an extradition hearing next year, a judge in London ruled on Friday, citing a “history of absconding,” according to British news agencies.
Mr. Assange had been scheduled to be released next week, after serving a 50-week sentence for jumping bail in 2012 and taking refuge in Ecuador’s London embassy rather than accepting extradition to Sweden to face a rape accusation.
But he is wanted in the United States, where he faces charges of conspiracy to hack government computers, and of obtaining and publishing secret documents in 2010.
Mr. Assange has also been under attack for Wikileaks’s release during the 2016 U.S. presidential campaign of thousands of Democratic Party emails stolen by Russian hackers, in what investigators say was an effort to damage the presidential campaign of Hillary Clinton.
But Mr. Assange, who denied that the emails were stolen, has not been charged in connection with their release.
At the hearing Friday, District Judge Vanessa Baraitser told Mr. Assange that as a person facing extradition, he would have to remain in prison, the BBC reported. “In my view I have substantial ground for believing if I release you, you will abscond again,” she said.
When asked if he understood what was going on, Mr. Assange, who appeared via video link from Belmarsh Prison in Southeast London, wearing a loosefitting T-shirt, said, “Not really.”
“I’m sure the lawyers will explain it,” he said, according to the British television network ITV.
Lawyers for Mr. Assange and other supporters have described him as in deteriorating physical and mental health. He was said to be too unwell to attend one previous hearing even by video link.
Mr. Assange’s legal team did not immediately respond to questions. According to ITV, his lawyers declined to make an application for bail on Friday.
Mr. Assange has been relying on the support of lawyers for years, as he fought multiple charges in different countries. Hailed as a hero for transparency by some, and cursed as a criminal by others, his latest appearances in the limelight have all been connected to those judicial proceedings.
While his role in publishing classified details of the United States’ military actions in Iraq and Syria have earned him praise, Wikileaks’s publication of Democratic Party emails alienated many supporters.
The United States has had Mr. Assange in its sights since 2010, when his organization published a giant trove of classified documents, mostly about the wars in Iraq and Afghanistan. Last year an indictment, accidentally unsealed, revealed a single count of computer hacking, saying he had conspired with the former Army intelligence analyst Chelsea Manning to hack into a Pentagon computer network.
After British police arrested Mr. Assange in April, dragging his frail, unkept figure out of Ecuador’s Embassy, where he had been living for seven years, the United States moved to formally request Mr. Assange’s extradition.
The Obama administration held back from pressing more serious charges against Mr. Assange. But things appeared different under President Trump. In May, the United States added 17 charges to the list, including violating the Espionage Act, a move that has raised profound First Amendment issues.
Mr. Assange’s extradition promises to be a long and difficult process, decided by the courts but complicated by questions of high-level diplomacy and politics.
In May, a United Nations expert who had visited Mr. Assange in prison said his punishment amounted to “psychological torture,” and accused Britain and the United States of “ganging up” on him.
A further complication came in May when Swedish prosecutors said they would reopen an investigation into the rape allegation against Mr. Assange.
If Sweden issued an arrest warrant, it would be up to Home Secretary Priti Patel — the British cabinet minister in charge of policing and security matters — to decide whether the American or Swedish request should have precedence.