WASHINGTON: US President George W. Bush on Monday invoked executive privilege in a bid to block testimony by two former aides to lawmakers looking into a scandal over a mass firing of prosecutors.

White House counsel Fred Fielding, Bush’s government lawyer, announced the move in a letter to the Democratic chairmen of the judiciary committees of the Senate and House of Representatives, raising the stakes in an increasingly tense constitutional stand-off.

Fielding repeated a White House offer to have his predecessor, Harriet Miers, and former Bush political strategist Sara Taylor, take lawmakers' questions in private, not under oath, and with no transcript or recording.

He said Bush was acting in good faith in invoking the protection, and refused lawmakers' request for documentation as well.

But Bush’s Democratic foes accused the White House of launching an unreasonable bid to subvert the power structure laid down by the US Constitution.

“This is more stonewalling from a White House that believes it can unilaterally control the other co-equal branches of government,” said Democrat Patrick Leahy, chairman of the Senate Judiciary Committee.—AFP