An internal FBI audit has found that the bureau potentially violated the law or agency rules more than 1,000 times while collecting data about domestic phone calls, e-mails and financial transactions in recent years, far more than was documented in a Justice Department report in March that ignited bipartisan congressional criticism. The new audit covers just 10 percent of the bureau's national security investigations since 2002. The vast majority of the new violations were instances in which telephone companies and Internet providers gave agents phone and e-mail records the agents did not request and were not authorized to collect. The agents retained the information anyway in their files. Two dozen of the newly-discovered violations involved agents' requests for information that U.S. law did not allow them to have. The results confirmed what ... critics feared, namely that many agents did not ... follow the required legal procedures and paperwork requirements when collecting personal information with one of the most sensitive and powerful intelligence-gathering tools of the post-Sept. 11 era -- the National Security Letter, or NSL. Such letters are uniformly secret and amount to nonnegotiable demands for personal information -- demands that are not reviewed in advance by a judge. After the 2001 terrorist attacks, Congress substantially eased the rules for issuing NSLs, [leading] to an explosive growth in the use of the letters. More than 19,000 such letters were issued in 2005 seeking 47,000 pieces of information, mostly from telecommunications companies.