President Barack Obama has suggested that surveillance methods used by US intelligence services may be reviewed following further spying revelations.
According to documents leaked by the whistleblower Edward Snowden, Britain and America monitored EU officials and the Israeli Prime Minister.
Speaking at a news conference at the White House, Mr Obama suggested that he may be ready to make some changes to the way phone records are collected.
Among dozens of recommendations he is considering, he hinted that he may strip the National Security Agency of its ability to store data in its own facilities and instead shift that storage to private phone companies.
"There are ways we can do it potentially, that gives people greater assurance that they're checks and balances, that there is sufficient oversight, sufficient transparency," Mr Obama said.
The new documents leaked by Mr Snowden reveal heads of state and international organisations were the focus of US and British spies.
The agents targeted a senior European Union official, German government buildings, and the office of a former Israeli prime minister, according to the papers published on Friday.
Other targets from 2008 to 2011 included foreign energy companies and aid organisations, according to The Guardian and The New York Times, citing secret documents from the former NSA contractor.
Mr Snowden's leaks have exposed the reported surveillance activities of the NSA and its British counterpart GCHQ, the alleged extent of which has upset many US allies and fuelled a heated debate about the balance between privacy and security.
He is living in Russia under temporary asylum.
The newspapers reported that in January 2009, GCHQ and the NSA had targeted an email address listed as belonging to the Israeli prime minister, who at the time was Ehud Olmert.
Spies also monitored email traffic between then-Israeli defence minister Ehud Barak and his chief of staff, Yoni Koren, the newspapers said.
Other targets were said to include the United Nations Children's Fund, French aid organisation Medecins du Monde, French oil and gas firm Total, and French defence company Thales Group.
An NSA spokeswoman said the agency did not use espionage to help US businesses.
"We do not use our foreign intelligence capabilities to steal the trade secrets of foreign companies on behalf of - or give intelligence we collect to - US companies to enhance their international competitiveness or increase their bottom line," the spokeswoman said.
The European Commission said if it was true one of its senior officials had been targeted it would be "unacceptable".
"This piece of news follows a series of other revelations which, as we clearly stated in the past, if proven true, are unacceptable and deserve our strongest condemnation," a spokesman said.
The Guardian said the disclosure that GCHQ had targeted German government buildings in Berlin was embarrassing for British Prime Minister David Cameron since he had signed an EU statement condemning the NSA's spying on Chancellor Angela Merkel.
GCHQ said it was aware of the reports but did not comment on intelligence matters.
A spokesman said: "Our work is carried out in accordance with a strict legal and policy framework which ensures that our activities are authorised, necessary and proportionate."
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