While Orioles first baseman Rafael Palmeiro chased historic hit No. 3,000 last month, he did so with the knowledge that he had failed a drug test.

According to a source familiar with the chronology, Palmeiro tested positive for a steroid in May and appealed the ruling in secret arbitration proceedings in June.

He then had to wait for an arbitration decision as he neared his 3,000th hit, which he got on July 15.

During that time, Palmeiro's situation was known only to certain representatives from Major League Baseball and the players union until it was made public Monday, the source said.

Newsday reported in today's editions that a source familiar with Palmeiro's drug test said the results showed positive results for stanozolol, which experts on steroids say is a "very tough steroid" that almost assuredly did not enter Palmeiro by way of accident or sabotage.

"If it's stanozolol, this was a deliberate act," said Gary Wadler, a Long Island doctor who is one of the world's foremost authorities on steroids. "The likelihood of sabotage is remote and improbable, and to suggest as much would be to send people on a wild goose chase."

Through a spokesman, Palmeiro's agent, Arn Tellem, citing an order of confidentiality, declined to comment about the test result.

Stanozolol has a long history in sports. Canadian sprinter Ben Johnson was stripped of his 100-meter gold medal in 1988 after testing positive for the drug.

The previously undisclosed chronology of Palmeiro's case has attracted the attention of Congress, largely because the first baseman emphatically told the House Government Reform Committee in March that he had never used steroids.

According to aides, the committee wants specific information from baseball about Palmeiro's case, including details of when his drug test was conducted, analyzed and disclosed to the player and the team.

Some committee members and staff members also want baseball to reveal what banned substance triggered the positive test.

The committee was drafting a tentative information request to baseball yesterday.

"Rafael was able to connect with Chairman Davis late this afternoon and assured him he will cooperate fully and provide his committee with any information it requests," Tellem, Palmeiro's agent, said yesterday, referring to Rep. Tom Davis, a Virginia Republican who is chairman of the committee.

The failed test was kept confidential during the lengthy appeal, and the source said some close to the situation, including the Orioles organization, did not learn of Palmeiro's positive drug test until Friday.

Arbitrator Shyam Das told the parties involved that he had denied Palmeiro's appeal, but he did not sign off on it until Monday, when it was released by Major League Baseball. That, not last weekend's Hall of Fame induction, delayed the suspension, the source said.

Palmeiro played in all three weekend games and did not appear distracted. He had four hits, including his 18th homer of the season, in 11 at-bats. He batted .299 with six homers and 19 RBIs last month.

As part of baseball's new drug policy, players are randomly tested and the urine is divided into two samples, A and B.

The lab first tests part of the A sample. If it comes up positive for steroids, the rest of that sample is tested. If that is also positive, Major League Baseball, the players union and the player are informed.

The player has the option of asking that sample B be tested. Also, the player can challenge the test with baseball's four-person Health Policy Advisory Committee, made up of a union representative, a baseball representative and two doctors.

If any one of the four decides that the challenge has merit, it is forwarded to a three-person arbitration panel consisting of a baseball lawyer, a union lawyer and an independent arbitrator.