Revelations from The Guardian that the US may have eavesdropped on the telephone calls of 35 world leaders has prompted a concern from the French and German governments.

The US National Security Agency memo from 2006 is one of a cache of documents leaked to The Guardian by former contractor Edward Snowden.

The Guardian's publication of details about the extent of UK and US surveillance activities have prompted a huge public debate and led to allegations that the information could aid terrorists.