WASHINGTON (Reuters) - Roger Clemens's lawyers defending him against perjury charges will get interview notes from the law firm that prepared a report accusing the former major league pitching star of using performance-enhancing drugs, a judge ruled on Thursday.

His attorneys had sought the notes from DLA Piper, which helped former Senator George Mitchell conduct a probe into steroids use in baseball, in an effort to undermine potential witnesses against Clemens.

In April the firm tried to block the request, arguing they were internal documents as they prepared the report and thus were protected.

But Judge Reggie Walton ruled that they should turn over notes and memoranda for trainer Brian McNamee and Kirk Radomski, a steroids dealer, that relate to Clemens.

"Heightened protection for these documents is not warranted because the statements contained therein are an accurate reflection of the witnesses' statements, not the attorneys' mental impressions of what the witnesses had stated or what the attorneys thought was important to record," Walton said.

McNamee is expected to be prosecutors' star witness when Clemens goes on trial starting July 6 on charges that he lied during a congressional investigation when he denied using human growth hormones and steroids.

The seven-time Cy Young award winner, has pleaded not guilty to three counts of making false statements, two counts of perjury and one count of obstructing Congress. He has steadfastly denied using performance-enhancing drugs.

DLA Piper has until Saturday to decide whether to appeal. If the firm does, that could lead to a delay in the trial.

(Reporting by Jeremy Pelofsky; Editing by Xavier Briand)