Brian McNamee’s lawyers said yesterday they gave federal prosecutors physical evidence backing the personal trainer’s allegation that Roger Clemens used performance-enhancing drugs.

“I think this is a significant point in the case. We believe that this is significant corroboration,” said McNamee’s lead lawyer, Earl Ward.

McNamee’s side turned over syringes with Clemens’s blood to IRS Special Agent Jeff Novitzky in early January, a person familiar with the evidence said, speaking on condition of anonymity because McNamee’s lawyers did not want to publicly discuss details. The syringes were used to inject Clemens with steroids and human growth hormone, the person said. A second person, also speaking on condition of anonymity, said the evidence was from 2000 and 2001. Lanny Breuer, one of Clemens’s lawyers, immediately responded that McNamee “apparently has manufactured evidence” and called all the allegations “desperate smears.”

“It is just not credible,” Breuer said in a statement. “Who in their right mind does such a thing?”

In December’s Mitchell Report on doping in baseball, McNamee said he injected Clemens with performance-enhancing drugs in 1998, 2000, and 2001.

Clemens, a seven-time Cy Young Award winner, gave a five-hour sworn deposition Tuesday to the House Committee on Oversight and Government Reform, and said afterward that he again denied using performance-enhancing drugs. McNamee is to give a deposition to the same committee today, ahead of a public hearing on February 13. By denying under oath that he used performance-enhancing drugs, Clemens put himself at legal risk if prosecutors determine his testimony wasn’t truthful.

Richard Emery, another of McNamee’s lawyers, said the committee will be given a description of the evidence that was turned over to prosecutors.

“It does change the nature of the case from a he-said, she-said to something about physical evidence,” Emery said.

He said he wouldn’t discuss until today why McNamee’s legal team waited until after Clemens’s deposition to go public with their discussion of physical evidence. Keith Ausbrook, the committee’s Republican general counsel, told the Associated Press the committee was not aware that such physical evidence existed.

“Unknown and unexpected evidence comes in at all times in any investigation,” Ausbrook wrote in an e-mail. “We will still need to examine McNamee’s evidence and hear what he has to say.”

McNamee, the former personal trainer for Clemens and Yankees pitcher Andy Pettitte, also told former Senate majority leader George Mitchell that he injected Pettitte with HGH. Pettitte confirmed in December that he used HGH for two days.

Emery said McNamee’s legal team planned to hold a news conference following their client’s deposition in Washington today and will discuss the evidence in greater detail then. Because the items were turned over several years after the events under discussion, Clemens’s side could challenge whether it was tampered with.

“Brian McNamee is obviously a troubled man who is obsessed with doing everything possible to destroy Roger Clemens,” Breuer said in a statement. “McNamee lied to the police who were investigating him for sexual assault, he lied to Senator Mitchell, he lied to the federal government, and now he apparently has manufactured evidence. He has changed his story repeatedly on this matter. He claims to love Roger Clemens, he says he modeled being a father on Roger Clemens, he said Roger treated him like family — but he now claims he kept blood, gauze, and needles from Roger Clemens for seven years. It defies all sensibility.”

Emery said it was unnecessary for McNamee’s side to persuade the Justice Department that the evidence was authentic.

“They’ll decide themselves what they believe is the case and make their own decisions based on the facts as they have it. All we know is what we believe is the truth,” Emery said.