NEW YORK — The chance that there will be no Major League Baseball season increased substantially Monday when the commissioner’s office told the players’ association it will not proceed with a schedule unless the threat of legal action by the union is resolved.

MLB informed the union it would announce a schedule and a date for the resumption of spring training if the union agrees to waive claims that MLB violated the March 26 agreement between the sides or if the union agreed to an expedited grievance procedure. MLB said absent a solution, the dispute would remain an impediment to starting play.

MLB’s action was described to The Associated Press by a person familiar with the details who spoke on condition of anonymity because no announcement was authorized.

Baseball Commissioner Rob Manfred said ahead of last week’s amateur draft that the chance of a season was “100%.”

“I can tell you unequivocally we are going to play Major League Baseball this year,” he said on ESPN’s draft broadcast.

He reversed his position Monday.