Rafael Palmeiro gave his first public explanation of his failed drug test Wednesday, on the eve of a congressional report on whether the former Baltimore Orioles slugger lied under oath when he denied using steroids.

In a statement released by his lawyer, Palmeiro acknowledged several facts of his case that already had been reported, including that the anabolic steroid stanozolol was found in his system in May, and that he had raised the possibility that a shot of vitamin B12 he took in April "might have been the cause."

"I have never intentionally taken steroids," Palmeiro said in the statement.

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When he testified before the House Government Reform Committee on March 17, alongside Mark McGwire, Jose Canseco and others, Palmeiro jabbed a finger in the air and said: "I have never used steroids. Period." On Aug. 1, baseball suspended Palmeiro for 10 days after he tested positive for steroids.

Two days later, Government Reform Committee chairman Tom Davis, R-Va., said the panel would open an investigation into whether Palmeiro committed perjury. A report on that investigation will be released Thursday, and Davis spokesman Dave Marin wouldn't comment Wednesday on the report's contents or Palmeiro's statement.

Major League Baseball executive vice president Rob Manfred declined comment.

"Nobody is more frustrated and disappointed in me than I am. Throughout my adult life, I have worked very hard on and off the field to live my life in an honorable way. All my accomplishments are now tainted, and many people have been hurt," Palmeiro said.

"I deeply regret the pain I have caused my family, my teammates, my fans and the game of baseball. I am sorry for the distraction that I have caused to the Orioles clubhouse and the League. I remain opposed to the use of steroids by athletes."

Palmeiro's case has been cited as one of the reasons that lawmakers have continued to pursue legislation to mandate tougher rules for steroid testing and harsher penalties for positive tests in baseball and other major professional sports leagues. The Senate appears to be nearing a vote on a bill calling for a half-season ban for a first steroid offense, a full-season ban for a second offense, and a lifetime ban for a third.

"Since I was informed last May that I tested positive for steroids, I have fully cooperated with Major League Baseball and Congress in their respective inquiries into this matter," Palmeiro said. "I have done so because I have nothing to hide."

Palmeiro — one of four players in baseball history with 3,000 hits and 500 homers — agreed to let Major League Baseball turn over to Congress information about the failed drug test.

Committee investigators also interviewed some of Palmeiro's current and former teammates and training partners. Those included two-time American League MVP Juan Gonzalez and Colorado outfielder Jorge Piedra, the second player publicly identified under the sport's new steroid rules when he was banned for 10 days in April.

When Palmeiro rejoined the Orioles after his ban, he said he would not speak about the case until Congress concluded its perjury investigation.

Palmeiro, 40, had just two hits in 26 at-bats after returning from his suspension and was booed by spectators at Baltimore and on the road. He was sent home to Texas to rehabilitate injuries; the Orioles eventually told him not to return to the team.