Roger Clemens arrives for a meeting with Rep. Diane Watson, D-Calif., on Tuesday. Clemens will testify at a Congressional steroids hearing today in Washington.

Washington ? Roger Clemens told Yankees teammate Andy Pettitte nearly 10 years ago that he used human growth hormone, Pettitte said in a sworn affidavit to Congress, the Associated Press learned Tuesday.

Pettitte disclosed the conversation to the congressional committee holding Wednesday’s hearings on drug use in baseball, a person familiar with the affidavit said. The person spoke to the AP on condition of anonymity because the document had not been made public.

According to the person familiar with the affidavit, who said it was signed Friday night, Pettitte also said Clemens backtracked when the subject of HGH came up again in conversation in 2005, before the same House committee held the first hearing on steroids in baseball.

Pettitte said in the affidavit that he asked Clemens in 2005 what he would do if asked by the media about HGH, given his admission years earlier. According to the account told to the AP, the affidavit said Clemens responded by saying Pettitte misunderstood the previous exchange in 1999 or 2000 and that, in fact, Clemens had been talking about HGH use by his wife in the original conversation.

“We don’t know what Andy said,” Clemens’ lead lawyer, Rusty Hardin, said in a statement e-mailed to the AP by his spokesman. “We look forward to hearing tomorrow.”

The news came on the eve of Clemens’ much-anticipated appearance to testify before the House Committee on Oversight and Government Reform. His former personal trainer, Brian McNamee, is today’s other main witness. McNamee told baseball investigator George Mitchell that he injected Clemens with steroids and HGH at least 16 times from 1998 to 2001. Clemens repeatedly has denied those allegations, including, he said, under oath in a deposition last week.

Pettitte also sat for a deposition at the beginning of last week, and had been scheduled to testify at the hearing. But he asked the committee to allow him to give an affidavit instead of appearing at the hearing, the person familiar with the document said. Pettitte was dropped from the witness list Monday.

McNamee also accused Pettitte of using HGH, and after the Mitchell Report’s release in December, Pettitte acknowledged that he did.