President Tito battled obstinately for life today as the country he has ruled for over 35 years pressed ahead with arrangements for a state funeral that could bring together leaders from both East and West.

The latest bulletin issued by doctors looking after the 87-year-old Yugoslav leader spoke of "a certain improvement" in his condition but official sources virtually ruled out any hope of recovery.

The medical bulletin, published at midday, read: "The certain improvement in the general health of President Tito which developed in the morning hours of Feb. 14 is being maintained. Intensive medical measures are under way with the aim of continuing and stabilizing this tendency."

Official sources interpreted the bulletin as a sign that the president's doctors, all Yugoslav professors of medicine, are determined to try every possible measure to reverse the general deterioration in his vital organs. Marshal Tito is understood to have survived a crisis on Wednesday night.

Until last Sunday, it had been widely believed that the World War ii guerrilla leader had been making a remarkable recovery following the amputation of his left leg on Jan 20. Last weekend, however, doctors revealed that his heart and kidneys had weakened.

Western diplomats here recalled the lengthy illness of Spain's generalissimo Francisco Franco five years ago, when he was kept alive by artificial means for weeks.

The collective leadership designated to succeed Tito has already demonstrated its ability to function smoothly. In the short term at least, no major upheavals are expected.

Officials have made clear they intend to stick by Tito's policy of nonalignment in world affairs. Ordinary Yugoslavs, however, have expressed concern at Soviet intentions toward their country after Tito's death.

Despite this undercurrent of concern, experienced analysts here doubt that Yugoslavia faces any immediate Soviet threat. A more plausible scenario is that, in the longer term, Moscow might seek to exploit different political or ethnic factions from behind the scenes here.

Authorities have already drawn up contingency plans to greet large numbers of important foreign guests expected for the funeral in the event of Tito's death. It is not known whom the Soviet leadership will send but many Western countries will be represented by either their president or their prime minister.

The marshal is expected to be buried either in Belgrade or in is home village of Kumrovec on the border of Croatia and Slovenia. At the time of his birth in 1892, this regon formed part of the Austro-Hungarian empire and Yugoslavia did not even exist.