LONDON, England (AP) — US investigators have gone to court to demand details about WikiLeaks’ Twitter account, according to documents obtained yesterday — the first revelation about the criminal case Washington is trying to build against those who leaked classified US documents.

WikiLeaks founder Julian Assange said he believed other American Internet companies such as Facebook and Google may also have been ordered to divulge information on himself and colleagues.

The US District Court for the Eastern District of Virginia issued a subpoena ordering Twitter Inc to hand over private messages, billing information, telephone numbers, connection records and other information about accounts run by Assange and others.

The subpoena also targeted Pfc Bradley Manning, the US Army intelligence analyst suspected of supplying the site with classified information; Birgitta Jonsdottir, an Icelandic parliamentarian and one-time WikiLeaks collaborator; and Dutch hacker Rop Gonggrijp and US programmer Jacob Appelbaum, both of whom have worked with WikiLeaks in the past.

The subpoena, dated December 14, asked for information dating back to November 1, 2009.

Assange blasted the US move, saying it amounted to harassment, and vowed to fight it.

“If the Iranian government was to attempt to coercively obtain this information from journalists and activists of foreign nations, human rights groups around the world would speak out,” he said in a statement.

A copy of the subpoena, sent to The Associated Press by Jonsdottir, said that the information sought was “relevant to an ongoing criminal investigation” and ordered Twitter not to disclose its existence to Assange or any of the others targeted.

But a second document, dated January 5, unsealed the court order. Although the reason wasn’t made explicit in the document, WikiLeaks said it had been unsealed “thanks to legal action by Twitter”.

The micro-blogging site Twitter declined to comment on the topic, saying only that its policy is to notify its users, where possible, of government requests for information.

Neither Facebook Inc nor Google Inc immediately returned messages yesterday seeking comment on possible subpoenas.

In Washington yesterday, the US government volunteered little new information about its ongoing criminal investigation against Assange and WikiLeaks after news of its subpoena leaked. Under rules governing grand jury investigations — in which US prosecutors present evidence and testimony to selected private citizens behind closed doors to seek their approval to formally file charges — government lawyers are not allowed to discuss the case until charges are announced publicly.

It was not immediately clear how the data being requested would be useful to investigators, but Twitter’s logs could reveal the Internet addresses that Assange and WikiLeaks supporters have been using, which could help track their locations as they travelled around the world. The information also might identify others with official access to WikiLeaks’ account on Twitter who so far have escaped scrutiny.

Assange’s lawyer, Mark Stephens, said targeting Twitter showed how desperate US officials were to pin a crime on the WikiLeaks founder.

“(This is an attempt to) shake the electronic tree in the hope some kind of criminal charge drops out the bottom of it,” Stephens told the BBC yesterday.

Jonsdottir said in a Twitter message that she had “no intention to hand my information over willingly.” Appelbaum, whose Twitter feed suggested he was travelling in Iceland, said he was apprehensive about returning to the US.

“Time to try to enjoy the last of my vacation, I suppose,” he tweeted.

Gonggrijp expressed annoyance that officials had misspelled his last name in the subpoena — and praised Twitter for notifying him.

News of the subpoena follows months of angry back and forth between US officials and WikiLeaks, which has released thousands of secret US military documents on the wars in Iraq and Afghanistan and more recently, thousands of classified US diplomatic cables.

US officials say posting the military documents put informers’ lives at risk, and that revealing diplomatic cables has made other countries reluctant to deal with American officials.

WikiLeaks denies that its postings put any lives at risk, saying that Washington merely is acting out of embarrassment over the revelations contained in the cables.

Assange is currently out on bail in Britain, where he is fighting extradition to Sweden on sex crimes allegations. His next hearing is scheduled for Tuesday.