The prospect of yet another round in the succession of aging and ailing Kremlin leaders whose presence cannot be counted on is posing long- term problems for Moscow's partners in the Warsaw Pact, who are tied so closely to the Soviet Union economically, militarily and politically, according to diplomats and Eastern European sources here.

The health of a Soviet leader made its way back onto the agenda of the Warsaw Pact after the scheduled mid-January summit of pact leaders was postponed because Soviet President Konstantin Chernenko was too ill to attend.

The short-term effects of the postponed summit on the Warsaw Pact itself are probably minimal, according to diplomats and Eastern European sources here, since on most major issues the course of the alliance is fixed and a temporary absence of the Soviet leader has little impact. But in this case, it inevitably raises questions, in Eastern Europe as elsewhere, about how long Chernenko will be in the job and what policies his successor, whoever he will be, will pursue.

Chernenko, not seen in public since Dec. 27, is now convalescing after an illness, Soviet sources said this week. The 73-year-old leader is known to suffer from emphysema, and while the nature of his current illness is not known, there have been reports that it was serious.

The first official comment on his whereabouts came yesterday, when a Foreign Ministry official said Chernenko is now "on winter holiday near Moscow."

Today, Chernenko gave written answers to an interview with Cable News Network, apparently in an effort to dispel rumors of his ailment. Foreign Ministry spokesman Vladimir Lomeiko told CNN that Chernenko is on a one-month vacation, although he did not know when it began. Lomeiko also denied the reports that the Soviet leader is seriously ill.

But so far, no new date has been set for the Warsaw Pact summit, originally scheduled to be held in Sofia, Bulgaria, in mid-January. For Moscow's allies in Eastern Europe, the waiting must be worrisome -- if only because of past history.

Another Warsaw Pact summit, scheduled for late 1982, was postponed because of then-president Leonid Brezhnev's failing health. It was finally held in January 1983, after Yuri Andropov came to power.

After this month's Sofia summit, Chernenko was scheduled for a state visit to Bulgaria, one that Andropov had canceled in October 1983 because of his own illness.

Still, the overall cohesion of the Warsaw Pact, at least in public, is unquestioned. Romania has carved out its own role -- refusing to take part in maneuvers or to allow Soviet troops on its soil -- but its basic loyalty is not at issue. Poland remains a concern for Moscow, but, for the moment, it does not represent cause for alarm.

Far more pressing for the Eastern Europeans are recent initiatives, approved last summer by the bloc's economic group, Comecon, for greater "integration" of the 10 member states' economies.

While not interfering in the "economic mechanisms" of individual countries provided they do not challenge the bloc's political orthodoxy, Moscow has pushed for more interdependence among its allies.

The Soviets, facing their own economic problems, are holding down -- although not decreasing -- the supply of oil and other raw materials to their allies. In return, they have called for the allies to export more and better consumer goods and foodstuffs to the Soviet Union.

But according to reports at the time of the Comecon meeting, Moscow's allies successfully resisted a Soviet proposal for a committee to coordinate economic planning within the alliance.

The postponed Sofia summit appeared timed to follow the Geneva meeting between Soviet Foreign Minister Andrei Gromyko and Secretary of State George P. Shultz that led to the resumption of nuclear arms talks.

For the Eastern European countries, the agreement in Geneva was undoubtedly welcome news. Like Western Europe, the Eastern Europeans had been anxious to see improved relations between the two superpowers for a mixture of economic and political motives.

Pressed by their own economic problems, Warsaw Pact members want relief from rising military spending and are eager to improve economic ties with the West.

In some countries, there are subtle internal political pressures. In East Germany, for instance, the Warsaw Pact's counterdeployment of Soviet nuclear missiles to offset NATO's new Pershing and cruise missiles has led to a fledgling peace movement that caused some discomfort for the leadership in East Berlin.

The postponement last fall of East German leader Erich Honecker's proposed visit to West Germany, apparently on Soviet orders, showed the limits of individual approaches from East to West.

But diplomats here agree that Moscow cannot afford to ignore pressure from its Eastern European allies and, without loosening its political control, has shown willingness to listen to their concerns.

While the main business of the Sofia summit was to have been the Geneva talks, the meeting also had been expected to address the question of an extension of the Warsaw Pact treaty itself, which is due to expire May 15 after 30 years.

According to some diplomats here, the only outstanding issue is the length of the new treaty. Romania, in its role as the pact's maverick, is said to be against a new treaty of indefinite duration.

Few observers here believe that there were any substantive disagreements behind the postponement of the summit since the Soviets would have wanted to be assured of unity before announcing it.

The date and site of a substitute meeting are unknown, but one Eastern European source said one plan may be to hold the summit in Moscow, on or before the 30th anniversary of the original treaty.

The key, many diplomats here believe, is Chernenko's health. As a candidate for the Supreme Soviet or parliament, he is scheduled to appear before his voters on Feb. 22, two days before the elections.

Greek Prime Minister Andreas Papandreou is expected here on a visit on Feb. 11, but according to diplomatic sources, the Greek Embassy has been told not to count on a meeting with the Soviet leader.

Today, Cable News Network was told that Chernenko would have given a personal interview had he not been "on vacation."