The health of Yugoslavia's President Tito has taken a turn for the worse following the amputation of his left leg three weeks ago. A medical bulletin issued by his eight-man medical team today reported digestion and kidney problems that, it said, had been slowing down Tito's recovery.

The report is being viewed with concern here since it contrasts sharply with earlier optimistic bulletins on the health of the 87-year-old Yugoslav leader. Until now, it had been assumed that Marshal Tito was making a remarkable recovery from two major operations last month -- and might even leave the hospital in the near future.

Today's bulletin, the first in three days, said Tito was undergoing further treatment in the hospital in the northwestern Yugoslav city of Ljubljana following what it described as "digestive troubles and the appearance of certain difficulties in connection with the kidney function."

Medical sources said the wording of the latest four-line bulletin was so imprecise that it could cover anything from minor complications to a major deterioration in the president's general state of health. But, in view of the closeness with which ordinary Yugoslavs are following every report on Marshal Tito's illness, it ws thought unlikely that the medical team would risk raising public concern unnecessarily.

The sources noted that the setback has occurred at a time when Tito is still in the postoperative danger period. His leg was amputated on Jan. 20 after the failure of an operation one week earlier to bypass an arterial blockage.

Following the amputation, the Yugoslav authorities managed to relieve the tense atmosphere surrounding the president's health by publishing pictures showing him in a wheelchair chatting happily with members of his family and senior Communist Party aides. He was also reported to have resumed some of his normal duties and to be taking a close interest in world affairs.

No photos, however, have been published of Tito for the last two weeks and reports on his condition have been scant.

The president's admission to the hospital last month sparked a flurry of speculation in Western capitals of possible Soviet moves against Yugoslavia after his death. Yugoslavia became the first communist country to break away from the Soviet Bloc in 1948. Since then it has maintained a honaligned stance in world affairs.

Yugoslav officials tried to dampen Western speculation and made it clear they would stick to President Tito's policies in the event of his death Arrangements for a smooth transition to a collective leadership composed of representatives of the country's many different nationalities appear to be well in hand.

Tito's two operations last month are now being viewed as a kind of dress rehearsal for the eventual transition to the post-Tito era. Officials here said they were encouraged by a display of public unity perhaps unmatched since the Soviet economic blockade of Yugoslavia 30 years ago.

A state of alert ordered last month, including the mobilization of reserve Army units, has since been relaxed. Nevertheless, in an interview with Yugoslav journalists, the chief of the defense staff, Adm. Branko Mamula, criticized neighboring countries for carrying out large-scale maneuvers near Yugoslavia's borders without informig Belgrade in advance.

He also revealed that, during the period of greatest concern for Tito's health, there had been some hoarding of esential foodstuffs and withdrawal of foreign currency from banks. Mamula called such signs of panic "needless." o