Major League Baseball on Tuesday took a stand against admitted steroid user Jose Canseco, calling the former slugger's allegations that the league might be playing favorites with some big-name players when it comes to positive drug tests "complete nonsense."

Canseco, who last played in the majors for the Chicago White Sox in 2001, returned to professional baseball with the independent San Diego Surf Dawgs on Monday in Chico, Calif.

Before the game, he made critical comments about how baseball officials are handling the new, stricter steroid policy, and he called for a "cleanup" in the commissioner's office.

Major League Baseball initially declined to react to Canseco's latest diatribe, in which he called baseball the "mafia" and suggested the sport isn't interested in knowing the truth about some standout players' use of performance-enhancing drugs.

But on Tuesday, the league strongly denied Canseco's statements.

"His allegations are complete nonsense," spokesman Rich Levin said.

"The policy sounds great, but that's not the problem," Canseco said Monday.

"There are major problems not with the policies but the individuals who are instituting this policy. For example, and this is theoretical, if Roger Clemens gets tested and he gets tested positive and it comes back, what do these individuals do with this policy? I think it's going to depend on a case-to-case, player-to- player basis."

Canseco's return - he went 0-for- 3 with three strikeouts and got hit by a pitch - comes about 16 months after he attracted the attention of Congress with an autobiography, Juiced, that accused several top players of using steroids.

ETC.: Boston pitcher Matt Clement cut short his first minor league rehabilitation start after one inning Tuesday with the Rookie-level Gulf Coast League Red Sox after hurting his biceps. It was Clement's first outing since going on the 15-day disabled list June 16 because of a right shoulder strain . . . The Mets purchased pitcher Jose Lima's contract from Triple-A Norfolk and optioned reliever Heath Bell to their top farm club . . . The Yankees have signed 16-year-old Venezuelan catcher Jesus Montero to a $2 million deal. The Yankees outbid Boston, Cleveland and the Mets for Montero shortly after the international signing period began late Saturday night, several newspapers reported. The 6- foot-3, 220-pound Montero is viewed as a possible successor to 34-year- old Jorge Posada behind the plate for the Yankees.