LONDON — Julian Assange moves like a hunted man. In a noisy Ethiopian restaurant in London’s rundown Paddington district, he pitches his voice barely above a whisper to foil the Western intelligence agencies he fears.

He demands that his dwindling number of loyalists use expensive encrypted cellphones and swaps his own the way other men change shirts. He checks into hotels under false names, dyes his hair, sleeps on sofas and floors, and uses cash instead of credit cards, often borrowed from friends.

“By being determined to be on this path, and not to compromise, I’ve wound up in an extraordinary situation,” Mr. Assange said over lunch last Sunday, when he arrived sporting a woolen beanie and a wispy stubble and trailing a youthful entourage that included a filmmaker assigned to document any unpleasant surprises.

In his remarkable journey to notoriety, Mr. Assange, founder of the WikiLeaks whistle-blowers’ Web site, sees the next few weeks as his most hazardous. Now he is making his most brazen disclosure yet: 391,832 secret documents on the Iraqi war. He held a news conference in London on Saturday, saying that the release “constituted the most comprehensive and detailed account of any war ever to have entered the public record.”

Twelve weeks ago, he posted on his organization’s Web site some 77,000 classified Pentagon documents on the Afghan conflict.

Much has changed since 2006, when Mr. Assange, a 39-year-old Australian, used years of computer hacking and what friends call a near genius I.Q. to establish WikiLeaks, redefining whistle-blowing by gathering secrets in bulk, storing them beyond the reach of governments and others determined to retrieve them, then releasing them instantly, and globally.

Now it is not just governments that denounce him: some of his own comrades are abandoning him for what they see as erratic and imperious behavior, and a nearly delusional grandeur unmatched by an awareness that the digital secrets he reveals can have a price in flesh and blood.

Several WikiLeaks colleagues say he alone decided to release the Afghan documents without removing the names of Afghan intelligence sources for NATO troops. “We were very, very upset with that, and with the way he spoke about it afterwards,” said Birgitta Jonsdottir, a core WikiLeaks volunteer and a member of Iceland’s Parliament. “If he could just focus on the important things he does, it would be better.”

He is also being investigated in connection with accusations of rape and molestation involving two Swedish women. Mr. Assange has denied the allegations, saying the relations were consensual. But prosecutors in Sweden have yet to formally approve charges or dismiss the case eight weeks after the complaints against Mr. Assange were filed, damaging his quest for a secure base for himself and WikiLeaks. Though he characterizes the claims as “a smear campaign,” the scandal has compounded the pressures of his cloaked life.

“When it comes to the point where you occasionally look forward to being in prison on the basis that you might be able to spend a day reading a book, the realization dawns that perhaps the situation has become a little more stressful than you would like,” he said over the London lunch.

Exposing Secrets

Mr. Assange has come a long way from an unsettled childhood in Australia as a self-acknowledged social misfit who narrowly avoided prison after being convicted on 25 charges of computer hacking in 1995. History is punctuated by spies, defectors and others who revealed the most inflammatory secrets of their age. Mr. Assange has become that figure for the Internet era, with as yet unreckoned consequences for himself and for the keepers of the world’s secrets.

“I’ve been waiting 40 years for someone to disclose information on a scale that might really make a difference,” said Daniel Ellsberg, who exposed a 1,000-page secret study of the Vietnam War in 1971 that became known as the Pentagon Papers.

Mr. Ellsberg said he saw kindred spirits in Mr. Assange and Pfc. Bradley Manning, the 22-year-old former Army intelligence operative under detention in Quantico, Va., suspected of leaking the Iraq and Afghan documents.

“They were willing to go to prison for life, or be executed, to put out this information,” Mr. Ellsberg said.

Underlying Mr. Assange’s anxieties is deep uncertainty about what the United States and its allies may do next. Pentagon and Justice department officials have said they are weighing his actions under the 1917 Espionage Act. They have demanded that Mr. Assange “return” all government documents in his possession, undertake not to publish any new ones and not “solicit” further American materials.

Mr. Assange has responded by going on the run, but has found no refuge. Amid the Afghan documents controversy, he flew to Sweden, seeking a residence permit and protection under that country’s broad press freedoms. His initial welcome was euphoric.

“They called me the James Bond of journalism,” he recalled wryly. “It got me a lot of fans, and some of them ended up causing me a bit of trouble.”

Within days, his liaisons with two Swedish women led to an arrest warrant on charges of rape and molestation. Karin Rosander, a spokesperson for the prosecutor, said last week that the police were continuing to investigate.