Under increasing pressure from Congress to eliminate the use of performance-enhancing drugs, Major League Baseball and its players' union announced tougher penalties against steroid use yesterday that include a lifetime ban for players who repeatedly test positive.

Under the new rules, which still must be ratified by both sides, players will be suspended for 50 games after one positive test, 100 games for a second offense and banned for life if they test positive a third time.

"This was a much deeper issue and that was an integrity issue," Commissioner of Baseball Allan H. "Bud" Selig said yesterday in a conference call. "It sends the right message."

Baseball has been under fire for more than a year since some of the game's most prominent sluggers were linked to steroid use as part of the federal investigation of the Bay Area Laboratory Co-Operative, or BALCO. The Burlingame, Calif.-based lab distributed so-called designer steroids, which were undetectable in testing at the time.

In March, current and former players were called to testify before the House Government Reform Committee about steroid use in the game. One of the players who testified that he had never used steroids, Rafael Palmeiro of the Baltimore Orioles, tested positive a few months later and was suspended.

Although the committee said it did not have enough evidence to pursue perjury charges against Palmeiro, Congress is considering legislation that would strip professional sports leagues of the power to police themselves in drug matters and instead institute a national standard modeled on the Olympics.

"Looking at it from my perspective I think it's unfair to get a 50-game suspension when it's not an intentional act," Palmeiro said in an interview last week. "This was not intentionally done by myself."

Barry Bonds of the San Francisco Giants, who is pursuing Hank Aaron's all-time home run record of 755, was called to testify but declined. According to grand jury testimony leaked to the San Francisco Chronicle last year, Bonds admitted he used substances provided by BALCO but said he didn't know what they contained. His personal trainer reached a plea agreement in the BALCO case. Bonds, 41, has never failed a drug test.

A month after the hearings, Selig proposed a 50-100-lifetime ban penalty structure. But as the summer wore on, several congressmen and senators introduced steroid bills increasing pressure on players and owners to take action. In September, the union's executive director, Donald Fehr, countered with a proposal of 20 games for a first offense, 75 for a second. The penalty for the third offense would have been decided at the discretion of the commissioner.

"I don't think of this as being that at all," Selig said yesterday when asked if baseball had broken the union's negotiators on the issue. "It was a matter of integrity in the sport."

Union officials were not available to comment, but Fehr issued a statement while traveling in the Caribbean.

"This reaffirms that Major League players are committed to the elimination of performance-enhancing substances and that the system of collective bargaining is responsive and effective in dealing with issues of this type," the statement read.

Lawmakers basked in their victory over baseball's players and executives, who had ranged from vague to defiant during the March hearing. Rep. Thomas M. Davis III (R-Va.), chairman of the House Government Reform Committee, said in an interview that both chambers were ready to pass tough testing legislation, which he believes pushed the union and owners to agree.

"This is appropriate oversight," said Davis, who met with several legislators to review the deal and spoke by phone with Selig. "What we did is the right thing. We were vindicated by the result."

Sen. Jim Bunning (R-Ky.), a former pitcher and a member of the Baseball Hall of Fame, said he would keep alive his bill, co-sponsored by Sen. John McCain (R-Ariz.), that would base penalties on the Olympic model, with a two-year suspension for a first positive test and a lifetime ban for a second. He is doing this, he said, to be sure yesterday's agreement will be ratified.

"I know that sometimes agreements that you were told were written in stone can somehow change and become open for interpretation," Bunning said. "So I and my colleagues will be watching very closely, and if things unravel we still have tough legislation we can move through Congress."

A key provision of the deal is the addition of amphetamines -- long a staple in baseball's clubhouses -- to the list of baseball's banned substances. Selig said yesterday that he didn't think the deal would have gotten done without provisions for amphetamine testing. Under the deal, a first positive test for amphetamines would require additional mandatory testing. A second offense would draw a 25-game suspension, a third offense would result in an 80-game suspension, and the penalty for a fourth would be at the commissioner's discretion.

Baseball officials said they will follow current government lists of banned steroids and amphetamines, but added they would fall short of World Anti-Doping Agency mandates that include substances such as nasal decongestants and allergy medications. This past season, under a toughened steroid policy, 12 players tested positive.

The new policy, if approved, will give baseball the toughest penalties for positive steroid tests among the country's four major professional sports leagues. Davis left open the option to pressure the others for similarly strict standards.

"I don't know how we can get it better than where we are right now," said Gene Upshaw, the executive director of the National Football League Players Association.

"A first-time offender in our program loses four games, and that's a quarter of the season. And we've never had anyone test positive for it twice. Only two players did test positive, and they both quit the game. Our policy has worked. Is it effective? Yes. I don't think Congress can do it any tougher than we already have it."

Staff writers Jorge Arangure Jr. and Leonard Shapiro contributed to this report.