President Barack Obama banned US eavesdropping on the leaders of close friends and allies on yesterday and began reining in the vast collection of Americans' phone data in a series of reforms triggered by Edward Snowden's revelations.

In a major speech, Mr Obama took steps to reassure Americans and foreigners alike that the United States would take into account privacy concerns highlighted by former spy contractor Mr Snowden's damaging disclosures about the sweep of monitoring activities of the National Security Agency (NSA).

"The reforms I'm proposing today should give the American people greater confidence that their rights are being protected, even as our intelligence and law enforcement agencies maintain the tools they need to keep us safe," he said.

While the address was designed to fend off concerns that US surveillance has gone too far, Mr Obama's measures were relatively limited.

Even as the White House put the final touches on the reform plan this week, media outlets reported that the NSA gathers nearly 200 million text messages a day from around the world and has put software in almost 100,000 computers allowing it to spy on those devices.

Mr Obama promised that the United States would not eavesdrop on the heads of state or government of close US friends and allies. A senior administration official said that would apply to dozens of leaders.

The step was designed to smooth over frayed relations between, for example, the United States and Germany after reports surfaced last year that the NSA had monitored the mobile phone of German Chancellor Angela Merkel.

"The leaders of our close friends and allies deserve to know that if I want to learn what they think about an issue, I will pick up the phone and call them, rather than turning to surveillance," Mr Obama said.

Still, he said, US intelligence would continue to gather information on the intentions of other governments, and would not apologise because US spy services were more effective.