The Justice Department plans to offer Boeing a plea deal related to a pair of fatal crashes involving its 737 Max plane more than five years ago, but the agreement would fall short of what families of the victims of those crashes had sought, a lawyer representing the families said on Sunday.

In a statement, the lawyers described the offer as a “sweetheart plea deal” and said that it would not force Boeing to admit fault in the deaths of the 346 people who died in the crashes in late 2018 and early 2019.

“The families will strenuously object to this plea deal,” Paul G. Cassell, a lawyer representing families and a University of Utah law professor, said in the statement. He added, “The memory of 346 innocents killed by Boeing demands more justice than this.”

The deal would include a fine, three years of probation and the appointment of an external monitor, Mr. Cassell said. The Justice Department was meeting with the families on Sunday afternoon.

It was not immediately clear whether the Justice Department had formally made the offer to Boeing. The Justice Department did not immediately responded to requests for comment. Boeing declined to comment.

This is a developing story. Check back for updates.