MOSCOW (AP) _ A senior aide to Boris Yeltsin suggested today that the Russian president has trouble maintaining a full-time work schedule due to poor health and should not even think about running for a third term.

``You can't say that Yeltsin is in ideal physical shape, that he's full of energy and activity to work round the clock,'' Igor Shabdurasulov, Yeltsin's recently appointed deputy chief of staff, said in an interview with the Russky Telegraph newspaper.

``It seems to me that he has become so tired, both physically and psychologically, that it outweighs every politician's natural desire for power,'' Shabdurasulov said.

His comments drew a swift response from Yeltsin's spokesman Sergei Yastrzhembsky, who said the aide ``expressed his own viewpoint, which does not reflect the opinion of the leadership of the presidential administration.''

Yeltsin's uncertain health periodically prompts rumors that he is seriously ill. A new round of unsubstantiated rumors began today, apparently originating in foreign financial markets.

The Kremlin said Yeltsin was well and holding meetings as planned.

Yeltsin and his doctors say the president, who underwent heart bypass surgery in November 1996, has fully recovered and is in good shape. Yeltsin makes regular public appearances and has made clear he intends to serve out his current term, which runs two more years.

However, the president spends much more time than before at his country residence outside Moscow. During the week, he rarely spends five full days working at the Kremlin. And while Yeltsin, 67, still makes working trips inside Russia and abroad, he travels less frequently than during his early years in office.

Shabdurasulov's comments were surprising because top Kremlin officials generally refuse to speak about the president's health.

Yeltsin has repeatedly said he does not intend to run for another term in 2000, but he has not flatly ruled it out.

Russia's constitution, approved in 1993, limits a president to two terms. But some Kremlin aides say that Yeltsin's first term, from 1991 to 1996, doesn't count because it began before the Soviet Union collapsed and the current constitution took effect. Russia's Constitutional Court is expected to rule on the issue later this year.

Shabdurasulov said Yeltsin himself is still hesitating about whether to run again. ``He hasn't made a firm decision yet,'' Shabdurasulov told the newspaper.

Shabdurasulov served as a spokesman for former Prime Minister Viktor Chernomyrdin, who was fired in March. In April, Shabdurasulov was named deputy presidential chief of staff in charge of media relations.