WASHINGTON — Roger Clemens' denial of steroid use warrants further investigation, Congress said today in asking the Justice Department to determine whether the star pitcher lied under oath in testimony to a House committee.

House Oversight and Government Reform Committee chairman Henry Waxman and ranking Republican Tom Davis sent a letter to Attorney General Michael Mukasey, urging more scrutiny of Clemens' statements in a Feb. 5 sworn deposition and at a Feb. 13 public hearing where he said he "never used anabolic steroids or human growth hormone."

"That testimony is directly contradicted by the sworn testimony of Brian McNamee, who testified that he personally injected Mr. Clemens with anabolic steroids and human growth hormone," the congressmen wrote.

"Mr. Clemens's testimony is also contradicted by the sworn deposition testimony and affidavit submitted to the committee by Andrew Pettitte, a former teammate of Mr. Clemens, whose testimony and affidavit reported that Mr. Clemens had admitted to him in 1999 or 2000 that he had taken human growth hormone," the letter said.

McNamee, Clemens' former personal trainer, told federal prosecutors, baseball investigator George Mitchell and Congress that he injected the seven-time Cy Young Award winner at least 16 times with human growth hormone and steroids from 1998 to 2001. Clemens repeatedly and vigorously denied the allegations.

Congress turned its attention to the matter because Clemens' denials of McNamee's allegations questioned the legitimacy of the Mitchell Report, prepared by the former Senate majority leader.

After both men stuck to their stories under oath, it was expected that one or the other — or perhaps both — would be referred to the Justice Department for a criminal inquiry. Instead, only Clemens faces additional scrutiny, after the committee decided not to refer McNamee.

His prominent place in the Mitchell Report tainted the legacy of Clemens, who ranks eighth in major league history with 354 wins. Now his legal fate could rest with the Justice Department, which must decide whether to follow the recommendation and open a probe.

"It's what we expected, but Brian is not joyful about this. No one is celebrating," said McNamee's lead lawyer, Earl Ward. "We think it's a sad and unfortunate situation that one of baseball's greatest pitchers now has the potential of being a defendant in a criminal case. Although we think it's the right decision, no one here is celebrating."

The Feb. 13 hearing generally divided along party lines, with Democrats giving Clemens a rougher time, and Republicans reserving their toughest questions for McNamee.

"Given the letter that the committee has sent out, the Republicans who attacked him owe him an apology because of the manner in which they went after him, calling him a 'drug dealer,' a 'liar,'" Ward said. "The decision to send out a referral letter says quite clearly that Brian McNamee told the truth."

Waxman and Davis jointly appealed to the Justice Department.

"For the good of the investigation and integrity of the committee, we've asked the Department of Justice to get to the bottom of this," Davis said.

Davis was the chairman of the committee when it held its 2005 hearing with Mark McGwire and Rafael Palmeiro.

Clemens' lead lawyer, Rusty Hardin, could not immediately be reached for comment after Waxman and Davis released their letter. But about 20 minutes earlier, when informed by The Associated Press that the criminal referral would be announced Wednesday, Hardin said: "It doesn't surprise me. We've always assumed there would be a referral if Roger testified differently from the Mitchell Report."

"We are not in a position to reach a definitive judgment as to whether Mr. Clemens lied to the committee," Waxman and Davis wrote to Mukasey. "Our only conclusion is that significant questions have been raised about Mr. Clemens's truthfulness and that further investigation by the Department of Justice is warranted. We ask that you initiate such an investigation."

Just last month, the same two congressmen asked for an investigation into whether 2002 American League MVP Miguel Tejada lied when he told committee investigators in 2005 that he never took performance enhancers and had no knowledge of other players using or talking about steroids. The FBI did open a preliminary inquiry into that case.

The committee pointed to evidence in the Mitchell Report — which was released in December — that it said contradicted statements given by Tejada, now with the Houston Astros.

Clemens was at the Astros' spring training camp in Kissimmee, Fla., on Wednesday, pitching in an indoor batting cage when the committee announced its decision. Clemens emerged to sign autographs and ignored several questions from reporters about what happened in Washington.

Clemens did not respond, then ducked into the minor league clubhouse.