The partly burned body of an unidentified man was found early yesterday morning in Arlington National Cemetery, lying in the eternal flame that burns at the gravesite of John F. Kennedy.

Authorities could offer no explanation for the macabre incident.

The body, which was reportedly fully clothed, was found lying face down over the recessed receptacle that holds the flame, according to the U.S. Park Police, which is investigating the death.

Although the body was burned on the chest and the lower extremities, according to one Park Police detective, the burns did not appear severe.

Investigators declined to speculate on whether the death was a homicide or suicide or due to natural causes. They said they also had not determined how long the man had been dead or whether he died at the cemetery.

An autopsy is scheduled today.

Detectives said the man carried keys and pocket change, but they found no wallet or papers or other means of identification. One source described him as in his 20s or 30s, and another said he appeared Hispanic or Oriental.

The body was found shortly after the cemetery gates opened at 8 a.m. by two tourists visiting from Louisiana.

The cemetery closes at 5 p.m. Authorities said they believed a routine check was made Saturday evening of the gravesite, on a hillside overlooking the Potomac River. Nothing unusual was reported then.

Although the gates are locked, a spokesman for the Military District of Washington, which operates the cemetery, said it would not be difficult to enter the area after hours.

A military guard is assigned at night to the Tomb of the Unknown Soldier, but no guard is assigned to the Kennedy gravesite, some distance away, and there is no night patrol in the cemetery, according to a spokesman. A civilian guard is assigned at night at the nearby Custis-Lee mansion, which is under U.S. Park Police jurisdiction. The grave of U.S. Sen. Robert F. Kennedy is about 100 feet away from where his brother is buried.

The visitors who discovered the burned body were identified as Mr. and Mrs. William Breese, of Starks, La. The couple, who reported the incident to police at 8:13 a.m., could not be reached last night for comment.

Yesterday's incident came six days after the anniversary of President Kennedy's assassination in Dallas on Nov. 22, 1963.

In an incident at President Kennedy's gravesite 10 years ago, a 23-year old Michigan man kneeled and stabbed himself in the chest, as tourists looked on. The man, who had told a friend he was having personal problems, died at Arlington Hospital several hours after the incident.