US President Barack Obama has ordered a review of the way US spy agencies gather intelligence following string of revelations which include bugging millions of phone calls.

During an interview with Fusion on Monday, he called for a review of the agency's operations, "to make sure that what they're able to do doesn't necessarily mean what they should be doing."

Obama said he is the "final user" of all intelligence gathered by the National Security Agency and other intelligence agencies in the US and that the White House gives the NSA "policy direction", but that "their capacities continue to develop and expand".

Earlier, the US Senate's intelligence committee has announced a major review of the country's surveillance operations.

The committee's chair, Diane Feinstein, said eavesdropping on leaders of friendly nations was wrong.

The Spanish El Mundo newspaper on Monday reported the US had monitored 60 million phone calls in that country during one month. The report comes days after similar stories of NSA spying in France and Germany.