The American government has closed down a website it created this year after inadvertently uploading information that could be used for building a nuclear bomb.

The site was set up in March as a showcase for reams of Iraqi documents captured during the war. The idea came from congressional Republicans who wanted to use the internet to highlight the threat posed by Saddam Hussein.

But the plan appears to have backfired when the site posted documents that amounted to a basic guide to building a nuclear bomb. The Bush administration closed down the website last night after questions were raised by the New York Times.

"It was a goofy idea, releasing all that sensitive stuff in the current climate with Iran supposedly trying to build a nuclear bomb," one diplomat told Guardian Unlimited, declining to be named because of the sensitivity of the issue.

He could have added that releasing details on nuclear bomb-building while the US is locked in a "war on terror" amounted to crass stupidity.

The New York Times quoted a spokesman for the director of national intelligence as saying that access to the site had been suspended "pending a review to ensure its content is appropriate for public viewing".

According to the paper, the documents contained charts, diagrams, equations and lengthy explanations about bomb-building, beyond what is available elsewhere on the internet and in other public forums.

The papers reportedly gave detailed information on how to build nuclear firing circuits and triggering explosives, as well as the radioactive cores of atom bombs.

The impetus for the online archive came from conservative Republicans, including the chairman of the House intelligence committee, representative Peter Hoekstra of Michigan.

Mr Hoekstra and other hardliners argued that dissemination of the Iraqi documents would reinforce the administration's contention that Saddam had posed a nuclear threat before the US-led invasion.

US arms experts after the war failed to find any evidence of weapons of mass destruction in Iraq and the American public has grown increasingly disenchanted with George Bush.

In April, after the first documents were made public, Mr Hoekstra issued a news release acknowledging "minimal risks," but saying the site "will enable us to better understand information such as Saddam's links to terrorism, weapons of mass destruction and violence against the Iraqi people."

He added: "It will allow us to leverage the internet to enable a mass examination as opposed to limiting it to a few exclusive elites."

But arms experts expressed alarm when the documents on Iraq's nuclear programme appeared on the website last month.

A senior American intelligence official told the New York Times that the documents showed "where the Iraqis failed and how to get around the failures".

The documents, he added, could perhaps help Iran or other nations making a serious effort to develop nuclear arms, but probably not terrorists or poorly equipped states.