Washington. The United States’ National Security Agency (NSA) illegally collected as many as 56,000 emails of US citizens annually between 2008 and 2011, according to declassified documents released by authorities.The US intelligence agency says that the collections were unintentional and due to technical issues, and that the emails were subsequently destroyed.The once-classified documents were released by US intelligence agencies on Wednesday as part of an unprecedented White House effort to smooth the uproar following revelations by former contractor Edward Snowden about the extent of secret government surveillance programmes.US officials say the documents show that intelligence collection programmes that inadvertently intrude on Americans’ privacy are found and fixed.The revelations also raise new questions, however, about operations by the NSA and the oversight of those operations by courts operating under the US Foreign Intelligence Surveillance Act (FISA)."The court is troubled that the government’s revelations regarding the NSA’s acquisition of Internet transactions mark the third instance in less than three years in which the government has disclosed a substantial misrepresentation regarding the scope of a major collection program,” Judge John Bates of the surveillance court wrote in one of the declassified documents.More specifically, Bates said in an October 2011 ruling that the court had concluded that the process that resulted in improper collections of the tens of thousands of emails was "in some respects, deficient on statutory and constitutional grounds”.The newly declassified documents can be found at on the website of the Director of US National Intelligence, James Clapper. Clapper authorised the declassification, partly in response to a lawsuit filed by the Electronic Frontiers Foundation, an internet civil liberties and rights group.The emails represent a small slice of the approximately 250 million email communications targeted for collection by the NSA every year.Under a separate programme, the NSA also keeps records on millions of phone calls made by US citizens and residents.