Former baseball slugger Mark McGwire told a congressional hearing Thursday that "there has been a problem with steroid use in baseball."

He will not, however, expose fellow players who have used the illegal drug.

"I do not sit in judgment of other players," he said, choking on a tear. "That has never been my style and I do not intend to change just because the cameras are turned on. Nor do I intend to dignify Mr. Canseco's book."

Former baseball great Jose Canseco's Juiced -- a tell-all book about steroid abuse in professional baseball -- was one of the catalysts for the hearing.

During his testimony, Canseco did confirm that he used steroids, but declined to make any new comments as he took his turn in front of the committee.

Canseco, named the American League Most Valuable Player in 1988, told the panel that "because of my fear of future prosecution . . . I cannot be candid with this committee."

Rafael Palmeiro was another former player who said Canseco's allegations about him are "absolutely false."

"I am against the use of steroids. I don't think athletes should use steroids and I don't think our kids should use them. That point of view is one, unfortunately, that is not shared by our former colleague, Jose Canseco."

Palmeiro then called Canseco an "unashamed advocate for increased steroid use by all athletes."

Current pitcher for the Boston Red Sox, Curt Schilling, was invited to appear before the panel today because of his outspoken opposition to the use of steroids in sport.

He did little to hide his disgust, calling Canseco a so-called author, and his book "a disgrace."

Schilling urged impressionable youth to not buy into the baseball best-seller.

"The allegations made in that book, having been made by one who for years vehemently denied steroid, use should be seen for what they are: an attempt to make money at the expense for others," he said.

Canseco took the harsh words without flinching, remaining stone faced and wearing his hair slicked back.

Ahead of the appearances by some of baseball's biggest stars, the chairman of the government panel had some stern words for pro baseball.

"Major League Baseball and the players' association greeted word of our inquiry first as a nuisance, then as a negotiation, replete with misstatements," Government Reform Committee chair Tom Davis said in his opening statement.

"I understand their desire to avoid the public's prying eye. ... But I think they misjudged our seriousness of purpose," he said. "I think they misjudged the will of an American public who believes that sunshine is the best disinfectant."

The first witness to appear before the congressional hearing Thursday morning was Hall of Fame pitcher, Kentucky Senator Jim Bunning.

Compared to the suspension he would have faced for cheating in his day, Bunning told the panel contemporary penalties are "pretty puny."

Old-time stars like Hank Aaron and Willie Mays didn't become better hitters as they aged, he added, contrasting that pattern with some modern players.

Baseball must act quickly to close the "Pandora's box," he warned, unless it wants the government to intervene.

"If baseball fails to fix this scandal, there are a lot of things we can do to get their attention - by amending the labor laws, repealing the outdated antitrust exemption that baseball alone enjoys, and shining the spotlight of public scrutiny," he said in a prepared statement.

The committee heard from more than a dozen witnesses including six subpoenaed Major League Baseball stars and league commissioner Bud Selig.

Because the committee does not offer immunity from prosecution, several of the players invoked their Fifth Amendment right not to answer questions.

But members of the committee warned the players that approach would be unwise.

Talking to the players, Davis said you "have an opportunity today to either clear their name or take public responsibility for their action, and perhaps offer cautionary tales to our youth."

Baseball rules

Members of the Government Reform Committee, the body holding the hearings, think baseball's current policy of suspending and shaming offenders falls short of what's needed to curb the practice.

To that end, Davis said Thursday that he is prepared to ask some hard questions about the steroid-testing policy Major League Baseball and its players agreed to in January.

Baseball was told that it must confront the role of steroids in its past, and Davis said one purpose of Thursday's hearing was to look at the steroid-testing policy baseball and its players agreed to in January.

"Baseball can not simply turn its back on recent history, pronounce that the new testing policy will solve everything, and move on," Davis said. "You can't look forward without looking back."

Although baseball officials have said a first-time steroid offence would result in an immediate 10-day suspension without pay and the public disclosure of his identity, the panel has said it believes the actual rules are not nearly so strict.

A draft of the sport's testing agreement released by the committee on Wednesday retains a controversial provision under which a player who tests positive for a performance-enhancing drug could be given a fine instead a suspension.

Even though a fourth-offence fine could climb as high as $100,000, the panel noted that some of the sport's stars make more than that in a single game.

Furthermore, the panel said, the rules fall short by allowing four steroids that are currently banned by the International Olympic Committee.

In his prepared statement to the panel, Selig said his league's new drug policy is, "as good as any in professional sports."

The Reform Committee had begun by inviting witnesses to appear voluntarily, but those offers went unanswered. When the panel issued subpoenas, baseball officials promised to fight back.

In turn, Davis said he would pursue contempt of Congress charges against anyone who refused to cooperate.

With files from the Associated Press