The FBI fabricated terrorism emergencies to obtain thousands of phone records between 2002 and 2006, it's been revealed.

The Bureau created "exigent letters" to get around rules that had already been significantly loosened by the Patriot Act. The letters were used to obtain some 2,000 phone records, The Washington Post reports.

Washington Post and New York Times journalists were among the targets.

The internal concerns were confirmed in emails that are part of an investigation by the Justice Department's inspector general, which is due to report this month.

As well as fabricating emergencies, FBI counter-terror investigators obtained phone records by simply leaning on operators, getting approval after the fact with blanket authorisations.

The Patriot Act allowed investigators to effectively self-certify their requests for communications data, using a "National Security Letter" (NSL), a type of subpoena without judicial oversight. The Justice Department has found that by fabricating emergencies and sending NSLs after it had obtained phone records, the FBI violated what civil liberties protections remained.

In response, the FBI claimed that although it did not follow statutory process to obtain the records, they were all legitimate targets for investigation.

"The [Justice Department] report is not expected to find — nor were there — any intentional attempts to obtain records that counterterrorism personnel knew they were not legally entitled to obtain," said assistant director of public affairs Michael Kortan.

He added all the numbers obtained have been deleted and that "steps were taken as early as 2006 to ensure similar situations do not occur in the future". However, The Washington Post said it had seen emails showing FBI lawyers sounded the alarm in 2005.

The US NSL system is similar to the UK's Regulation of Investigatory Powers Act (RIPA) regime for authorities to obtain communications data from phone companies and ISPs. Each has no judicial oversight and investigators effectively self-certify their requests.

The UK system is much broader, however, with no requirement that national security is threatened and many more agencies, such as local councils, empowered to access records.

Oversight is provided by a former High Court judge appointed by the Prime Minister, who produces an annual report. In 2008, the most recent available, he says that 595 errors were made but added: "I am not convinced that any useful purpose would be served by providing a more detailed report of these errors."

The government is developing a major extension to communications surveillance that would require internet firms to retain huge amounts of extra data, under the Interception Modernisation Programme. Ministers have argued that that RIPA will be sufficient to govern access to the newly available terabytes of private information. ®