WASHINGTON - Major League Baseball challenged the authority yesterday of a House committee that issued subpoenas ordering seven current and former baseball stars, including two Orioles, to appear at a hearing next week on steroid use.

Baseball's challenge raised the specter of a showdown in Congress or the courts.

The House Government Reform Committee said in a prepared statement that it had "no alternative" but to issue subpoenas because six of the players "made it clear - either by flatly rejecting the invitation to testify or by ignoring our repeated attempts to contact them - they had no intention of appearing."

The six are Orioles Sammy Sosa and Rafael Palmeiro, Jason Giambi of the New York Yankees, retired former home run king Mark McGwire, Frank Thomas of the Chicago White Sox and Curt Schilling of the Boston Red Sox.

The only subpoenaed player who agreed in advance to testify was retired slugger Jose Canseco.

Sosa, Palmeiro, Giambi and McGwire were named in a recent "tell-all" book by Canseco as possible steroid users.

A central purpose of the hearing, a top committee aide said yesterday, is to try to determine the validity of Canseco's widely publicized allegations.

"The committee is trying to do something very simple and something baseball should have done on its own: find out what happened," said Phillip Schiliro, chief of staff for Rep. Henry A. Waxman of California, the panel's top-ranking Democrat.

"You had Canseco making new allegations, and they are serious. But what the committee doesn't know, and what the American people don't know, is whether they are true."

Schiliro said players didn't seem to be taking the hearing seriously, using as an example Palmeiro's statement that he might not attend because the March 17 hearing falls on his wife's birthday.

"I've worked on hearings for 20 years, and we've never had a witness say, 'It's my wife's birthday,'" Schiliro said.

Palmeiro, interviewed at spring training in Florida, said he felt victimized: "I don't know what my link is. I shouldn't have been in the book in the first place." Palmeiro has denied taking steroids.

Sosa declined to comment.

Sosa's agent, Adam Katz, told CNN that the slugger had "respectfully" declined the committee's invitation but will now have to "take a second look and make the right choice."

Canseco alleges in the book that Palmeiro, formerly of the Texas Rangers, and two Texas teammates "would bring their steroids to the ballpark and I would inject them there, the same way I used to inject McGwire back at the Oakland Coliseum."

Palmeiro said yesterday: "There are 100 names in the book. What are they going to do, bring in 100 people? I feel like a victim now. I get put in a book I don't belong in, and now I may have to go testify before Congress."

But Major League Baseball said the committee was overstepping its powers by trying to compel testimony that could violate players' privacy and interfere with a federal investigation.

The investigation is looking into BALCO, a California laboratory at the center of a scandal involving baseball and football players and track and field stars.

At least one of the players subpoenaed yesterday - Giambi - has appeared before a BALCO grand jury and could be called to testify at a trial.