REDDING, Conn. (AP) _ The father of a U.S. Army officer shot to death by a Soviet guard in East Germany in 1985 says it was ''very gross'' of the Pentagon to fail to tell the family that Moscow had apologized.

The Soviet Union's highest-ranking military official apologized last month during the Moscow summit for the shooting death of Maj. Arthur D. Nicholson Jr., the Pentagon announced Tuesday.

Nicholson's parents said it was the first they had heard about the apology. Nicholson's mother, Jean Nicholson, said she was pleased to hear an apology had been made, but ''we've had no word from the government at all.''

''I never thought this would happen,'' she said of the apology.

Nicholson's father, Arthur Sr., said he called his son's widow in Washington, and she said she hadn't heard of the apology.

''I'm somewhat distressed that nobody made any effort to notify us,'' he said. ''I think this is very gross.''

Nicholson said he did not want to comment on the apology itself until he heard its contents.

The apology was extended by Soviet Defense Minister Dmitri Yazov to Defense Secretary Frank C. Carlucci at a private meeting May 31, said Dan Howard, the Pentagon's chief spokesman.

Yazov offered no new details or explanation for the March 24, 1985, shooting, nor did he respond to previous U.S. demands for financial compensation to Nicholson's family, Howard said.

Nonetheless, ''we feel we have received the appropriate apology from the Soviets,'' the spokesman said.

In addition, Howard said, ''The two sides agreed to come up with a list of recent such incidents, violations, whatever, and to meet again to try to work out a set of ground rules.''

Howard quoted Yazov as saying: ''I express my regret over the incident and am sorry this occurred. This does not promote improved relations. Secretary Carlucci and I have agreed we will do all we can to prevent these kinds of incidents in the future.''

Howard disclosed the apology during a regular Pentagon briefing. He said he did not disclose it at the summit because no reporters asked about the matter.

Nicholson, 37, was a member of the U.S. Military Liaison Mission, allowed under a 1947 treaty to keep tabs on Soviet military activities inside East Germany.

Nicholson and a driver, Sgt. Jessie G. Schatz, were trying to observe a Soviet tank shed during a surveillance mission. According to the U.S. account, Nicholson was close to - but not in - a restricted area when a Soviet sentry suddenly opened fire without warning.

The Pentagon has charged that Schatz was prevented from going to the wounded man with his first aid kit and that the major was left to die without medical attention.

The Soviets have said Nicholson was improperly wearing a camouflaged uniform, had strayed into a restricted area and ignored shouted warnings before the sentry opened fire.