By Lily Kuo

WASHINGTON (Reuters) - Former Major League Baseball player David Segui testified on Thursday in the perjury trial of Roger Clemens that the pitching ace's personal trainer told him he had saved needles that he claims he used to inject Clemens with performance-enhancing drugs.

Segui told the court that trainer Brian McNamee said he had saved needles "as evidence" to placate his wife, who was concerned about McNamee's relationship with the pitcher. McNamee, in separate testimony, has said he kept needles used to inject Clemens with anabolic steroids in 2001 to calm his wife by stashing evidence of the pitcher's alleged drug use.

"He mentioned that the relationship between Brian and Roger had put stress on (his) married life," the former first baseman said in U.S. District Court in Washington, describing a phone conversation with McNamee in 2001.

"He said she had raised the idea of keeping evidence ... he mentioned that he kept darts (needles) to get his wife off his back," said Segui, who has admitted he used steroids obtained from Kirk Radomski, a convicted steroids dealer who also supplied McNamee.

Radomski testified earlier in the trial that he mailed human growth hormone to Clemens' home.

McNamee testified last week that he had injected Clemens with steroids and human growth hormones from 1998 to 2001 and held onto used needles and other waste to allay his wife's concerns.

Anthony Corso, a friend and client of McNamee in New York, can also be called by the government to testify, Judge Reggie Walton ruled. A defense filing says McNamee allegedly told Corso that Clemens used human growth hormones "regularly" and that McNamee had saved evidence from 2001.

Clemens' attorneys have worked to paint McNamee, the star prosecution witness, as a liar who has obtained immunity in exchange for his testimony. Testimony from Segui and Corso could bolster prosecutors' charges that Clemens had used performance-enhancing drugs but denied doing so to Congress - the basis of the perjury charge.

Testimony from Segui and Corso could help shore up McNamee's credibility, after he acknowledged he had lied to officials about his knowledge of the case.

McNamee testified last week, for instance, that he kept quiet on stashed medical waste from a 2001 injection even though federal agents and an independent study into steroids in baseball headed by former Senator George Mitchell had asked him if he had evidence of Clemens' alleged drug use.

Clemens, 49, is being tried for a second time on federal charges of lying in 2008 to the U.S. House of Representatives' Committee on Oversight and Government Reform, which was investigating drug use in Major League Baseball. His first trial ended last year in a mistrial.

In other testimony, Pamela Reynolds, a forensics expert with the FBI's chemistry unit, said she had found evidence of different steroids on medical waste from the 2001 injection that McNamee had turned over to authorities.

Clemens, a seven-time winner of the Cy Young Award winner as best pitcher in his league, has said McNamee injected him with shots of vitamin B12 and the anesthetic lidocaine instead of performance-enhancing drugs.

The trial is scheduled to run until June 8.

(Reporting by Lily Kuo; Editing by Anthony Boadle and Philip Barbara)