President Bush has been answering questions from federal prosecutors in the CIA leak probe.
The White House says the president was quizzed for just over an hour in the Oval Office by U.S. Attorney Patrick Fitzgerald's team.
They're trying to find out who blew the cover of a CIA operative after her husband, a former ambassador, emerged as a key critic of the administration's Iraq policy.
Bush was joined by a Washington attorney, who's now been formally retained as the president's lawyer.
Press Secretary Scott McClellan wouldn't talk about what questions were asked or say if Bush answered them all. But he insists the president views the leaking of classified information as a "very serious matter" and wants the culprit found.
The spokesman notes Bush has ordered the White House staff to cooperate with the probe. And he says Bush was "pleased to do his part."