The National Security Agency (NSA) reported its own violations of surveillance rules to a United States intelligence court and promised additional safety measures to prevent repeat of similar missteps again, according to more than 1,000 pages of newly declassified files about the federal government’s controversial programme of collecting every American’s phone records during the past seven years.

According to court records from 2009, after repeated assurances that it would obey the court’s rules, the NSA acknowledged that it had collected material improperly. In one instance, the government said its violations were caused by “poor management, lack of involvement by compliance officials and lack of internal verification procedures, not by bad faith”. In another case, the agency said it improperly collected information due to a typographical error.

District Judge John Bates of the intelligence court said in the 2009 case that, since the government had repeatedly offered so many assurances despite the problems continuing, “those responsible for conducting oversight at the NSA had failed to do so effectively”. Mr Bates called his conclusion “the most charitable interpretation possible”.

The Obama administration published the files on Monday as part of an ongoing civil liberties lawsuit challenging the constitutionality of the government’s collection of phone records, which the White House has said is important to countering terrorism. The files published were so heavily censored that one of the two justifications for the government to search through Americans’ phone records was blacked out.

The latest release reflects the administration’s strenuous efforts to maintain its legal authority to collect citizen’s phone records amid opposition in Congress.

Meanwhile, in a legal victory for the administration, the Supreme Court on Monday refused to intervene in the NSA controversy. It rejected a call from a privacy group to stop the agency from collecting the telephone records of millions of Verizon customers in the US. Other lawsuits on the topic are making their way through lower courts around the country. AP