NEW YORK - The head of the Major League Baseball players' union Monday rejected Commissioner Bud Selig's proposal to significantly increase penalties for steroid use, saying the current policy was working out fine.

In an open letter to union chief Donald Fehr, Selig proposed a 50-game suspension for players testing positive for steroids for the first time, a 100-game suspension for second-time offenders and a lifetime ban for any player caught a third time.

Selig also called for more random testing and a ban on amphetamines.

Under the current policy, agreed by the owners and players and which went into effect on March 10, players are suspended for 10 days after the first positive test, 30 days following a second offence and 60 days for a third.

In a letter to Selig dated May 1, Fehr said: "The players support the current program and are confident that it will deter the unlawful use of steroids and are understandably reluctant to renegotiate the existing agreements."

Selig's proposal followed intense pressure on baseball to beef up its performance-enhancing drugs policy after a poor showing before a U.S. congressional committee hearing in March.

Several congressmen sharply criticized baseball's drugs policy as weak and threatened to introduce legislation creating tougher policies for U.S. professional sports.

"Performance-enhancing substances undermine the integrity of the competition on the field," Selig wrote in his April 25 letter to Fehr.

Fehr made his letter to Selig public on the same day as Minnesota Twins relief pitcher Juan Rincon was suspended for 10 days after testing positive for a banned substance.

Rincon, 26, was the fifth player to be barred this season under baseball's new testing policy.