The anonymous internet phenomenon Wikileaks.org today won two influential allies in its fight against a US court order shutting down the website.

Wikileaks disclosed secret documents on Guantanamo Bay, Northern Rock and other controversial issues before a Swiss bank won a legal injunction that blocked its US server last week.

But two groups that frequently challenge the Bush administration on its wiretapping programme and its treatment of terrorist suspects came to its defence today. The American civil liberties union (ACLU) and the Electronic Frontier Foundation filed a legal motion on behalf of Wikileaks users, defending their right to access the website without censorship.

"Journalists, academics, and the general public have a legitimate interest in accessing the materials found on Wikileaks in order to inform their work and participate in public debate," ACLU staff attorney Ann Brick said in a statement.

"Blocking access to the entire site in response to a few documents posted there completely disregards the public's right to know. It's unconstitutional and un-American."

In a separate court filing today, an alliance of American reporters filed a motion supporting on behalf of Wikileaks, arguing that the website's closure violates the freedom of speech guaranteed in the Constitution.

The alliance — which includes the Associated Press, Gannett news service, the Los Angeles Times newspaper and other media outlets — cited the famous "Pentagon Papers" case of 1971, when the administration of Richard Nixon sought a restraining order against newspapers that published leaked documents on the Vietnam war.

"Under [the] Pentagon Papers [case], the first amendment prohibits prior restraints [on freedom of speech] in nearly every circumstance, even where national security may be at risk and the … source is alleged to have obtained the documents unlawfully," the media alliance wrote in its filing.

It was not a risk to US national security that prompted the court order shutting Wikileaks. Instead a Swiss bank convinced a judge appointed by George Bush to close the website after a former bank employee leaked documents that purport to show the company engaged in money laundering and tax evasion.

The next step in the case will come on Friday, when a court hearing is scheduled to determine whether the preliminary shutdown order can stand. In the meantime, fans and supporters of Wikileaks have rallied to its defence by setting up "mirror" copies of the website that include most of the incriminating documents at issue in the case.