The Bush administration will tell the Senate today that the National Security Agency's programme for terrorist surveillance has been badly distorted by media reports, and that the scheme is a strictly limited one aimed at al-Qaeda members and affiliated groups.

In the first Senate hearing on the controversial programme, which was set up secretly in 2002 and revealed publicly in December, Alberto Gonzales, the attorney-general, will say that the press accounts "are in almost every case, in one way or another, misinformed, confused or wrong," according to Time magazine, which has obtained documents outlining the planned testimony.