July 31 (Bloomberg) -- Roger Clemens’s onetime trainer, Brian McNamee, sued the former Major League Baseball pitcher, saying he has been defamed by Clemens’s allegation that McNamee lied when he told investigators that the pitcher used steroids.

Clemens’s actions in launching a “vociferous campaign to discredit McNamee, despite knowing that McNamee’s statements were true, were extreme and outrageous,” the former trainer said in a complaint filed today in federal court in Brooklyn, New York. McNamee seeks damages for emotional distress.

McNamee said in the complaint that he injected Clemens with steroids during the 1998, 2000 and 2001 baseball seasons, as well as with human growth hormone in 2000. In 2007, McNamee was approached by federal investigators who made him provide information for former U.S. Senator George Mitchell’s investigation of steroid use in baseball, according to the complaint.

After Clemens was named in the Mitchell Report, he denied using steroids and human growth hormone and accused McNamee of deceit and defamation, according to the complaint. In 2008, Clemens sued McNamee for defamation.

“We’re very comfortable with the court resolving this whole issue,” Rusty Hardin, Clemens’s lawyer, said in a telephone interview.

The case is McNamee v. Clemens, 09-1647, U.S. District Court, Eastern District of New York (Brooklyn.)

To contact the reporter on this story: Edvard Pettersson in Los Angeles at epettersson@bloomberg.net.

Last Updated: July 31, 2009 22:00 EDT