The Consumer Product Safety Commission yesterday warned that certain automatic baseball pitching machines are hazardous, and nationally have resulted in between 25 and 35 serious injuries, including skull fractures, permanent paralysis, brain damage, loss of sight and broken bones.

At a press conference held at Hains Point, commission Chairman S. John Byington displayed one machine which had no guard around the arm, and, Byington said, can represent a serious threat even after it is unplugged.

When the pitching arm is cocked, it can, without warning, release and strike someone standing next to it, the CPSC claims.

Byington said there were about 7,500 of the electric- or gas-powered machines in use, and said they may be labeled either "Dudley" or "Commercial Mechanisms."

The commission has gone to court to force distributors of the machine to modify the device by putting a guard around the mechanism and to sell all future machines with the guard in place.

Attorneys for Dudley and its parent, Athlome, the firm distributing the pitching machine, have fought the CPSC in court, claiming that the machine is safe if users follow instructions.

Attorney Michael Healy of Athlome said his firm sent instructions to machine owners last fall on how to safely use the machines, which were distributed by Commercial Mechanisms Inc. of Kansas City, and which have not been manufactured since December, 1975.

The CPSC is asking consumers not to use the machine, and to disengage the pitching arm until a protective guard is put on.

The defendents went into federal court in the District yesterday in an attempt to prevent the CPSC from making public statements about the potential hazards of the machine, but the motion was defeated.

"These machines are being used by Little Leagues, schools and children," Byington said at the press conference after the court ruling.

"People believe the pitching arm is in a safe position when it is not," he added, "and when they are playing with the machine, coaches have been injured, kids have been paralyzed and blinded."

Byington said the reason he had not held a press conference sooner, since the commission field suit last July, was that "we thought we could work things out with the manufacturers before the baseball season."

But, he said, "At this point the manufacturers are not willing to enter into the kind of agreement we want, so we are asking people to disconnect the machines until they get fixed.

Attorneys for the manufacturers say they are willing to put proper warnings on the machines and contend that if the arm is disconnected after use there is no problem.

In its court filing, the CPSC included affidavits from some 30 people injured by the machines.

One affidavit was from a 56-year-old Texas woman who had attended a home-run-hitting contest. The pitching machine used in the contest had been unplugged and put aside.

"I learned over in front of the machine to get a closer look at it and suddenly and without warning the pitching arm rotated forward and struck me in the left forehead, eye and cheek," she said.

After several visits to the hospital, including two one-week stays and eye surgery, she still has no vision in her left eye.