After 13 days of treatment for a heart condition in the Central Clinical Hospital, President Boris Yeltsin was transferred Monday to a sanatorium outside the capital for an unspecified period of convalescence, with aides insisting that he was feeling well and in full control of affairs of state.


Presidential press secretary Sergei Medvedev told Itar-Tass that Yeltsin, 64, had moved to a sanatorium in Barvikha, west of Moscow, after finishing his course of treatment and being discharged. "The president is feeling well," he said.


Evidence of the president's adherence to a work schedule included a decree issued Monday ap But analysts said Yeltsin's prolonged absence from office, coming in the wake of speculation about his physical health and heavy drinking, would nevertheless fuel doubts about his continuing ability to fulfill his role as president, particularly if he should decide to run for a second term in June 1996.


"A man of his age, who has gone through everything that Yeltsin has -- he has the right to get sick," said Michael McFaul, a political analyst with the Moscow Center of the Carnegie Endowment. "But even before he went into hospital, there was a sense that the Yeltsin era was coming to an end."


In a television interview from the hospital last Tuesday -- Yeltsin's first public appearance since being admitted for treatment on July 11 -- he said he had suffered a heart attack, which had involved "some unpleasantness," but that he had begun to recover two days after entering the hospital.


This version of events contrasted sharply to that put out at the time by Kremlin aides, who said on the day he entered hospital that Yeltsin's condition had returned to normal and that he was continuing to perform his duties.


A constitutional provision for the temporary hand-over of power to Prime Minister Viktor Chernomyrdin was not applied. Government spokesman Viktor Konnov said he saw "no grounds, either legally, or practically, for temporary transfer of powers."


Chernomyrdin himself went ahead with a planned trip to Yakutia on July 14, after telling journalists that he had spoken with Yeltsin by telephone and was assured that he was feeling better.


Given Yeltsin's own subsequent account of his illness in the televised interview -- during which he was short of breath and a little pale, but otherwise looked reasonably healthy -- such optimism on Chernomyrdin's part might have been premature. Was it possible that Yeltsin's inner circle could have been keeping the truth even from Chernomyrdin?


According to McFaul, the possibility should not be ruled out. "Mr. Korzhakov is very protective," he said, referring to Alexander Korzhakov, the hawkish chief of Yeltsin's bodyguard, who is widely believed to have considerable influence on the president's decision-making and has been accused frequently in the past by more liberal figures of limiting their access to Yeltsin or denying it altogether.


"There were certainly a lot of ambiguities," McFaul said. "They never kicked in the constitutional process."


But Irina Kobrenskaya of the U.S.A.-Canada Institute believes it unlikely that Chernomyrdin would fall prey to such deception: "Chernomyrdin does not look like a man who is easily misled. He has a good sense of reality -- he would know whether he could go ahead with his trip to Yakutia."


Kobrenskaya argues that the contradictions arose more out of ineptitude and inexperience on the part of Yeltsin's spokespersons than any conspiracy, as well as a tendency to fall back on old habits. This would also explain the bungled issue of the first official hospital picture of Yeltsin, which bore a remarkable resemblance to shots taken three months earlier.


"But it is very difficult to believe anybody now, because there have been so many lies in the past," Kobrenskaya said. "Maybe this time we suspect too much."


As a public relations exercise, the Kremlin's efforts to play down Yeltsin's sickness have been disastrous. The affair of the photographs was greeted with contempt by the Russian press. The irreverent Moskovsky Komsomolets and the respected daily Segodnya published both pictures side by side, with the former asking its readers to spot three differences and the latter making the more taxing demand to find ten.


The weekly Argumenty i Fakty responded to the official description of Yeltsin's ailment as an "ischemic disease of the heart," by issuing its own list of "facts" about the condition, which it said threw doubts on the diagnosis.


As to whether the current speculation would die down, Kobrenskaya thought everything depended on events over the next days and weeks. The failure of the current peace negotiations could provoke another crisis and again put Yeltsin's health and capabilities under the spotlight.


"But if nothing happens, it will go quiet," she said.


McFaul pointed out that the timing of Yeltsin's illness worked in his favor, with the whole country winding down for the summer vacation, which Yeltsin has rarely allowed political developments to interrupt.


"Even back in '91," he said, "when the whole country was crashing down around him, he still spent most of September -- at least three weeks -- on vacation."