The US intelligence community has pledged to disclose more data about government surveillance programmes by reporting annually how many secret court orders are issued to telecommunications companies under certain legal rules.

Director of National Intelligence James Clapper has announced a plan to release the total number of legal orders issued every 12 months to telecom companies by the secret Foreign Intelligence Surveillance Court, and the number of targets affected by those orders.

The court orders, under authority granted by the Foreign Intelligence Surveillance Act and National Security letters, allow collection of information about subscribers and call records, both for past communications and ongoing wiretaps.

But only the aggregate annual numbers of these court orders will be made public.

The move is part of President Barack Obama's response to criticism about a lack of transparency in government surveillance programmes following leaks by former spy agency contractor Edward Snowden.

"This is a good start as it pulls back the covers a bit on the government authorities, but we still need more information," said Marc Rotenberg, president of the Electronic Privacy Information Centre advocacy group.

It urged further disclosures about the cost and effectiveness of the surveillance.