Barack Obama's new privacy watchdog has delivered its first bark, with a letter to intelligence chiefs urging them draft stronger rules on domestic surveillance, something it revealed had not been updated for 30 years.

The intervention of the Privacy and Civil Liberties Oversight Board, its first since the appointment of new staff by the White House earlier this year, came as Obama acknowledged that technology was outpacing the checks put in place to protect privacy and said the National Security Agency was "scary to people".