Germans in US talks over spying claims
A German delegation of intelligence officials is in Washington for talks at the White House on Wednesday following claims that the US monitored Chancellor Angela Merkel's mobile phone.
The Chancellor's foreign policy advisor and Germany's intelligence co-ordinator will hold talks at the White House.
The head of US intelligence has defended the monitoring of foreign leaders as a key goal of operations.
The US is facing growing anger over reports it spied on its allies abroad.
It has also been reported that the National Security Agency (NSA) monitored French diplomats in Washington and at the UN, and that it conducted surveillance on millions of French and Spanish telephone calls, among other operations against US allies.
However, NSA director Gen Keith Alexander said "the assertions... that NSA collected tens of millions of phone calls are completely false".
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.
German media have reported that the US bugged German Chancellor Angela Merkel's phone for more than a decade - and that the surveillance only ended a few months ago.
Germany's delegation includes Christoph Heusgen, Mrs Merkel's foreign policy adviser, and Guenter Heiss, the secret service co-ordinator, NSA spokeswoman Caitlin Hayden said.
US National Security Adviser Susan Rice, Director of National Intelligence James Clapper and Lisa Monaco, assistant to the president for homeland security and counterterrorism, are also expected to take part.
Ms Hayden said the meeting was part of the agreement reached between President Barack Obama and Chancellor Merkel last week to deepen US-German cooperation on intelligence matters.
'Basic tenet'
The meeting comes just hours after Mr Clapper and Gen Alexander testified before the intelligence panel of the House of Representatives on Tuesday.
Gen Alexander said much of the data cited by non-US news outlets was actually collected by European intelligence services and later shared with the NSA.
Meanwhile, Mr Clapper told lawmakers that discerning foreign leaders' intentions was "a basic tenet of what we collect and analyse".
He said that foreign allies spy on US officials and intelligence agencies as a matter of routine.
Mr Clapper said 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 BBC's Jonny Dymond in Washington says if anyone was expecting apologies or embarrassment from the leaders of America's intelligence community, they were in for a disappointment.
The intelligence pair were not given a tough time by the committee but that sentiment is turning within Congress toward tightening up the reach of American intelligence agencies, our correspondent says.
Russia spy claims
Meanwhile, the spokesman for Russian President Vladimir Putin has denied that Moscow used free USB memory sticks and mobile phone charging cables to spy on delegates attending the G20 Summit in St Petersburg last September.
Reports in two Italian newspapers suggested that the USB sticks and cables had bugs on them that could steal data from the delegates.
Spokesman Dmitri Peskov said the reports were an attempt to distract from the problems between European countries and the US.