A document providing confidential details of US civilian nuclear sites was accidentally posted on the internet, the government has admitted. The 266-page document included the precise location of stockpiles of fuel for nuclear weapons, the Obama administration said. The Government Printing Office website took down the posting on Tuesday after experts expressed concern. US officials insisted the information detailed was not a security threat. The document, which lists itself as “sensitive but unclassified”, contains maps and information on hundreds of US civilian nuclear sites. No military installations are included but the document does cover the nuclear weapons laboratories at Los Alamos, Livermore and Sandia.