(CNN) -- Major League Baseball and players have agreed to ramp up the battle against illicit performance-enhancing drugs by instituting in-season testing for human growth hormone.
Team owners and the Major League Baseball Players Association, in a statement Thursday, said unannounced, random blood tests for human growth hormone -- known as HGH -- will begin this year.
The timing of the announcement comes the day after the National Baseball Hall of Fame announced that no former players were selected for induction from a ballot that included some stars who have been linked to performance-enhancing drugs.
One, pitcher Roger Clemens, was said by a former teammate, pitcher Andy Pettitte, to have taken HGH. Clemens denied the allegation, saying he was misheard. Pettitte admitted to using the hormone once a dozen years ago.
Seven-time Most Valuable Player Barry Bonds also was implicated in HGH use but has said he never knowingly used banned substances.
HGH is not approved by the Food and Drug Administration as a treatment for sport injuries and is banned by most professional sports leagues.
HGH is naturally occurring, according to the World Anti-Doping Agency.
"The major role of HGH in body growth is to stimulate the liver and other tissues to secrete insulin-like growth factor (IGF-1). IGF-1 stimulates production of cartilage cells, resulting in bone growth and also plays a key role in muscle and organ growth," WADA says on its website.
A WADA-accredited lab in Montreal, Canada, will conduct the random blood tests.
The MLB agreement also calls for enhanced efforts to detect testosterone.
A previous agreement allowed testing for HGH during spring training, in the off-season and for reasonable cause. The testing now will include the regular season.
Testing has been done in the minor leagues since 2010, and last season Mike Jacobs, a player for the Colorado Rockies' top farm team, became the first player to test positive. He was suspended for 50 games.
"This agreement addresses critical drug issues and symbolizes Major League Baseball's continued vigilance against synthetic human growth hormone, testosterone and other performance-enhancing substances," Commissioner Bud Selig said in the statement.
Michael Weiner, executive director of the players group, said, "Players want a program that is tough, scientifically accurate, backed by the latest proven scientific methods, and fair; I believe these changes firmly support the players' desires while protecting their legal rights."
Under Major League Baseball policy, a first violation will be punished with a 50-game ban, a second will lead to a 100-game suspension. On the third strike the player will be suspended for life.