President Tito's health was officially reported to have worsened today, raising fears that his life may be in imminent danger.

Doctors attending the 87-year-old Yugoslav leader reported that he was undergoing intensive medical treatment following a futher weakening of his kidneys and heart. The complications developed three weeks after his left leg was amputated.

As Yugoslavs braced themselves for a possible transition to the post-Tito era, the country's top political and military leaders met in emergency session to review defense arrangements. Yugoslavia broke away from the Soviet Bloc in 1948, and senior officials have made clear that after Tito's death they intend to continue his policy of strict nonalignment in world affairs.

Unitl last Sunday it had been assumed that Tito -- the last survivor of the World War II generation of charismatic leaders -- was making a spectacular recovery from two major operations on his leg. In the last four days, his condition has been reported steadily worsening.

Tonight's bulletin, issued on nationwide television news, reported: "In the course of today, the general condition of President of the Republic, Josip Broz Tito has worsened. A further weakening in the functions of the kidneys and the heart has developed. Intensive measures are being undertaken."

The bulletin was signed by the council of eight Yugoslav professors of medicine who have been responsible for the president's treatment since he entered the clinic in Ljubljana, in northwestern Yugoslavia, just over a month ago. It is the best equipped clinic for heart treatment in the country.

Western diplomats here with access to official sources believe that President Tito's vital organs are in a final stage of deterioration. But they stress that it is impossibile to predict how long he might survive in this condition in view of modern medical techniques.

Tito, however, is believed to have nowish for his life to be prolonged by artificial means and was reportedly initially opposed to the amputation of his leg on Jan. 20.

Tito, who has ruled this Balkan country of 22 million people for the last 35 years, has refused to designate a successor. According to the constitution, on his death the functions of head of state and president of the Yugoslav League of Communists will be taken over by collective leadership composed of representatives of each of Yugoslavia's different nationalities.

Despite rising concern for the President's health, Yugoslav officials sought to project an image of "business as usual" in line with their claim that the political situation in Yugoslavia is at present very stable. The prime minister, Veselin Djuranovic, went ahead with a scheduled visit to East Germany.

The office of the prime minister, however, is not as important in Yugoslavia as in some other European countries. President Tito's key military and political aides have remained in Yugoslavia throughout his illness.