The White House will this week step up efforts to defend its policy on the Patriot Act as well as its controversial decision to conduct domestic surveillance on US citizens without a warrant from a judge, in the face of mounting concerns from civil liberties groups.

President George W. Bush began the counter-offensive with a strong defence of his decision in 2001 to authorise the National Security Agency to eavesdrop on those suspected of links to al-Qaeda and of his legal authority to prosecute the war on terror.