Commissioner Peter Ueberroth said yesterday he believed in the innocence of players who testified before a Pittsburgh grand jury investigating possible drug trafficking involving major league baseball players.

About a dozen players were granted immunity and testified before the federal grand jury. The group includes Lonnie Smith of the St. Louis Cardinals, Tim Raines of the Montreal Expos and Rod Scurry of the Pittsburgh Pirates -- all of whom went through rehabilitation for chemical dependency problems.

The commissioner would not say if he has talked with federal authorities involved in the Pittsburgh probe. "I will tell you, though, that I feel the players who testified are innocent," he said in New York.

Ueberroth said he hoped to have a drug program, including mandatory testing for all baseball personnel except major league players, in place within one month.

"It's a sensitive issue," the commissioner said. "I want to collect a couple of missing links on the program. I'd like to get all the details together before discussing it further.

Meanwhile, the Milwaukee Sentinel reported yesterday that at least 10 players from the Milwaukee Brewers, Cleveland Indians and Chicago White Sox were drug customers of a man convicted of drug conspiracy.

Seven of the 10 players are still active, the paper said. Six of the players are current members of the Brewers or were team members from 1979 through 1982. The other players were then members of the Indians or Chicago White Sox, but are no longer with those teams.