President Boris Yeltsin was hospitalized today, suffering from what Kremlin aides described as flu and a high temperature, adding to speculation about his health troubles and his ability to rule.

Yeltsin, who has remained out of public view as Russian troops have moved into the northern section of the breakaway region of Chechnya, was taken this morning to the elite Central Clinical Hospital.

Spokesman Dmitri Yakushkin said today that Yeltsin became ill on Friday. Yakushkin had told reporters that day that Yeltsin needed a vacation, but in a radio interview this morning he said "doctors decided it was best for him to be taken to hospital today" for treatment.

"Flu can take several forms, but I think we are talking at least several days here," he said. Yeltsin planned to watch a Russia-Ukraine soccer match tonight from his hospital bed, the spokesman said.

This is the third time this year Yeltsin has been hospitalized; he has suffered a string of illnesses in recent years, some of which have kept him away from the Kremlin for weeks at a time. The illnesses have included bronchitis, pneumonia and a bleeding ulcer.

He underwent quintuple coronary artery bypass surgery in November 1996, and there has been speculation recently that he may need a second operation. He has often appeared confused and lost, which some sources have ascribed to a circulatory problem.

The newspaper Sevodnya reported today that Yeltsin may go to Germany for heart surgery, but Yakushkin called the report "complete nonsense." And Michael E. DeBakey, the American heart surgeon who has advised Russian doctors on Yeltsin's condition, said Friday he had not heard anything about new heart problems.

On Aug. 16, Yeltsin told reporters that "my heart is working like a clock," and he insisted his blood pressure was 120/80 and his pulse was stable at 64. "It means the heart is working well!" he insisted.

In the past, Yeltsin's absences have had an impact on his ability to rule, often leaving the country in the hands of subordinates. Currently, Russia is mounting a major military operation in Chechnya, and is also on the eve of a new parliamentary campaign season.

CAPTION: Boris Yeltsin has stayed out of public view during Chechen conflict.