The White House has acknowledged the need for additional "constraints" on US intelligence gathering, amid reports the nation spied on its allies.

Spokesman Jay Carney said an ongoing White House intelligence policy review would account for "privacy concerns".

His remarks come amid reports the US eavesdropped on political leaders and collected data on phone calls in Germany, France, Spain and Brazil.

An EU delegate in Washington described the row as "a breakdown of trust".

Jonny Dymond reports