The Bush administration has ordered federal agencies to scour the content of their public websites for sensitive data potentially useful to terrorists.
White House Chief of Staff Andrew Card sent a memo to the heads of all agencies and executive departments, asking for an immediate re-examination of all public documents.
The move could bring about the withdrawal of thousands of papers, records and reports that have been available to the public for years.
White House press secretary Ari Fleischer claimed that the move is to prevent terrorists "from using our technology against us once again".
According to Card, federal offices have until 19 June to review the content of their websites for "sensitive but not classified" material and report back to Office of Homeland Security director Tom Ridge.
Besides documents on weapons of mass destruction, Fleischer said that the review includes "anything that could threaten national defence or information that could be misused to harm the security of our nation and the safety of our people.
"This is serious business. There is information in a pre-11 September environment that should be viewed in a different context than post-11 September."
But Ari Schwartz, associate director of the Center for Democracy and Technology, argued that the big concern is the creation of a new category of information called "sensitive but unclassified".
"Even the idea of this category runs counter to the spirit of the US Freedom of Information Act," he explained. "If it is not a threat to national security, and therefore classified, then it should be made readily available."
Schwartz added that the new policy gives those who would like to conceal information an easier platform to do so.
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