Dianne Feinstein, the chairwoman of the US Senate Intelligence Committee, said she is "totally opposed" to the NSA collecting intelligence on its allies and said that oversight of such surveillance needs to be strengthened,
Her comments follow reports that the US has spied on German chancellor Angela Merkel for years and monitored millions of Spanish phone calls.
Ms Feinstein said: "Unless the United States is engaged in hostilities against a country or there is an emergency need for this type of surveillance, I do not believe the United States should be collecting phone calls or emails of friendly presidents and prime ministers."
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One story dominates Thursday's front pages with some newspapers printing emotive pleas to voters to keep the United Kingdom as one.
After a mild start temperatures should pick up, with the south of England seeing highs of 26C.
In Edinburgh tonight you can hear it and feel it. The buzz, the banter of the day and the thrilling sense something big is coming tomorrow.