U.S. President Barack Obama sought on Wednesday to reassure Angela Merkel, the German chancellor, that controversial US surveillance of telephone and email records was limited and subject to strict legal controls.

U.S. President Barack Obama sought on Wednesday to reassure Angela Merkel, the German chancellor, that controversial US surveillance of telephone and email records was limited and subject to strict legal controls.

“We are not rifling through the emails of German citizens or American citizens or French citizens or anyone else,” Obama declared in Berlin.

At a press conference in the chancellor’s office, the US president insisted that his intelligence services monitored telephone traffic simply in order to identify any telephone calls to numbers that had already been flagged as suspicious, and were only allowed to listen in to calls after submitting their request to a federal judge.

He said such surveillance “applies very narrowly to leads that we have obtained on issues related to terrorism or the proliferation of weapons of mass destruction”.

“I am confident that at this point we have struck the appropriate balance [between surveillance and protecting people’s privacy,” Obama claimed, adding that 50 threats had been averted through the surveillance programs.

“Lives have been saved,” Obama said.

The subject of US surveillance of phone calls and the internet, conducted by the National Security Agency, was raised by Merkel in her talks with the US president, who is on a one-day official visit to the German capital.

The concerns follow allegations earlier this month by former intelligence contractor Edward Snowden of widespread internet and telecoms surveillance.

Merkel told reporters that the Internet was "new territory" for everyone and offered new possibilities to be abused by "enemies and opponents" but urged the need for "proportionality".

Obama also flatly denied that Germany was used as a base for launching or operating US unmanned drones.