Baseball Commissioner Bud Selig called for tougher penalties for major leaguers who violate the sport's drug agreement, a move the union is willing to consider, but not for the 2013 season.

Speaking at a news conference on Saturday at the Arizona Diamondbacks' spring training ballpark, Selig said last year's positive drug test for All-Star Game MVP Melky Cabrera and allegations players received banned substances from a now-closed Florida anti-aging clinic helped lead him to seek stiffer penalties as quickly as possible.

He declined to give specifics, saying MLB Executive Vice-President Rob Manfred and players' union head Michael Weiner will meet.