Head of US intelligence defends spying policy

The head of US intelligence has told lawmakers that discerning foreign leaders' intentions is a key goal of the nation's spying operations.

Director of National Intelligence James Clapper said such efforts were a "top tenet" of US intelligence policy.

But he told the intelligence panel of the House of Representatives the US did not "indiscriminately" spy on nations.

Clapper was reacting to a growing international row over reports the US eavesdropped on foreign allies.

"Leadership intentions is kind of a basic tenet of what we collect and analyse," Clapper said, adding that foreign allies spy on US officials and intelligence agencies as a matter of routine.

He said that what he called the torrent of disclosures about American surveillance had been extremely damaging and that he anticipated more.

But he said there was no other country that had the magnitude of oversight that the US had, and that any mistakes that had been made were human or technical.

The testimony came amid a series of reports in the international news media that the NSA had spied extensively on the leaders, diplomats and citizens of nations friendly to the US, including Brazil, France, Germany, Mexico and Spain.

The revelations stem from documents leaked by fugitive ex-US intelligence contractor Edward Snowden, who now lives in Russia and is wanted in the US in connection with the unauthorised disclosures.

President Barack Obama has faced significant criticism over reports he was unaware of the extent of the spying.

In a television interview, the US president said the country's national security operations were being reassessed to ensure the NSA's growing technological capability was kept under control.