Washington AFP-JIJI

In a reversal, President Barack Obama will hand lawmakers classified documents outlining the legal justification for drone strikes that kill U.S. citizens abroad who are conspiring with al-Qaida.

An administration official disclosed the move Wednesday on the eve of a Senate hearing on Obama's nomination of top White House counterterrorism adviser John Brennan to lead the Central Intelligence Agency in the president's second term.

Some senators had warned Brennan's confirmation could be in doubt if the administration did not share more information on the legal and constitutional grounding for the government killing its own citizens.

The disclosure also comes after NBC News published an unclassified Justice Department white paper covering similar ground, reigniting the debate about the killing of estranged Americans who switched sides in the "war on terror."

Obama aides insist that killing al-Qaida suspects, some of them U.S. citizens, in places like Pakistan or Yemen, complies with U.S. law and the constitution, even when no intelligence links the targets to specific attack plots.