Part of a child's body containing fragments of glass and metal was found off northern Japan today, and officials speculated that the body might be that of a child who died when a Soviet fighter plane destroyed a Korean Air Lines passenger jet Sept. 1.

Kyodo news service reported tonight that the body part had been found in waters northeast of Hokkaido, Japan's northernmost island. The precise locations was not given.

Other press reports quoted officials as saying the upper body of a child between 6 and 11 years old had been recovered. There were metal fragments in the head and glass fragments in the chest.

Local officials said an autopsy showed the child had been dead for one to two weeks.

The apparent site of the body's recovery suggested that it could have drifted southeast from the crash site in the Sea of Japan.

The Soviets have not permitted Japanese search crews to enter Soviet territorial waters off the island of Sakhalin, where the plane was shot down by a Soviet missile.

Soviet diplomats reported to the Japanese government that Soviet search crews had found no bodies as of tonight.

Six metal fragments and other materials were washed up on a beach near the Japanese town of Wakkanai today and were recovered by citizens and police. They could not be officially identified as coming from the downed aircraft, although local authorities said one fragment appeared to be from the tail of an American-made plane. The downed plane was a Boeing 747.

The Soviet ambassador to Japan, Vladimir Pavlov, told the Foreign Ministry last night that his government would soon give Japan some documents and materials recovered by the Soviet search ships.

Japanese officials said tonight they had not been informed when or where the debris would be handed over.