In a statement, Turner said 15 judges on the US Foreign Intelligence Surveillance Court on 36 occasions over the past seven years have approved the NSA's collection of US phone records as lawful.

Also on Friday, government lawyers turned to US Court of Appeals for the District of Columbia Circuit to block one federal judge's decision that threatens the NSA phone records program.

The opposing lawyer who spearheaded the effort that led to the ruling said he hopes to take the issue directly to the Supreme Court.

The Justice Department filed a one-page notice of appeal asking the appeals court to overturn US District Judge Richard Leon's ruling last month that the program was likely unconstitutional. The government's move had been expected.

Larry Klayman, who filed the class-action suit against US President Barack Obama and top administration national security officials, said he intends to petition the federal appeals court next week to send the case directly to the Supreme Court. Klayman said the move was justified because the NSA case was a matter of great public importance.