The Soviet Union's failure to provide its own citizens and its European neighbors with timely information about the Chernobyl nuclear disaster is prompting concern here about the ability of the Soviet bureaucracy and communications systems to respond to an international emergency.

While the Reagan administration appears to seek propaganda gains from attributing the information vacuum to willful decisions by Soviet leaders to suppress information, diplomats and other westerners here are increasingly concerned about the likelihood that the compartmentalization and rigidity of the Soviet system itself may have caused much of the confusion, and may prevent effective responses to control such disasters in the future.

This impression grows from the unease shown by officials in Moscow in addressing sensitive details of the case and their early confusion about who should answer questions. They appear worried about which Soviet officials will eventually face the political fallout for what many experts consider the world's worst nuclear catastrophe and for Soviet leader Mikhail Gorbachev's first domestic crisis.

The original two-day gap in public information in the Soviet capital about the disaster, followed by a relative flurry of official activity, has created an impression that only inquiries from abroad called the attention of senior officials in Moscow to the case, according to a consensus of western envoys here.

The political fallout in the Soviet Union could bring change within the ruling Politburo, since some Kremlinologists feel blame could settle on Vladimir Shcherbitsky, the Ukranian party boss who would have to shoulder some responsibility for the failure of local officials to notify Moscow quickly enough.

Shcherbitsky, 68, is one of the few remaining holdovers on the Politburo from the era of Leonid Brezhnev's leadership. Gorbachev has managed to dispose of most of the others in consolidating his control, but has thus far been unable to dislodge Shcherbitsky.

Only last Tuesday -- at least three days after the disaster began -- did the Soviet presentation of it begin to bear the marks of the concern for public relations that has characterized Gorbachev's 14 months in office, and then only minimally.

Without press briefings or direct knowledge of when and how the Soviet leadership learned about the disaster and what orders ensued, a western reporter in the Soviet capital is left with scattered images to form an impression of how the Kremlin's information channels function in an emergency.

In this case, the images suggest that information about the original explosion in Chernobyl was kept at local or low levels for too long, allowing the problem to burgeon and provoke international outrage -- and perhaps to spark leadership squabbles.

Last Monday, two days after the explosion at the nuclear plant, Foreign Ministry press spokesman Vladimir Lomeiko left the Soviet Union, reportedly unaware of the disaster. He said in New York on Friday that he obviously would not have left had he been aware of the crisis.

Later Monday, an official at the Soviet Atomic Energy Commission told a Moscow-based Swedish diplomat that "we have no information" about a possible reactor problem. A few hours later, a mid-level Foreign Ministry official would not acknowledge to anxious Swedish and Danish diplomats that any difficulty had emerged. "At that point, it was unclear what they knew, if anything," a Scandinavian diplomat said in an interview here.

Late Monday evening, Soviet television and the official news agency Tass reported, in a four-sentence dispatch, that an "accident" had occurred at Chernobyl. For 24 hours, all queries about the cause and possible health hazards were referred back to that sparse statement.

Thereafter, the Kremlin's publicity machine came alive, with official statements nearly daily, meetings between Soviet officials and senior diplomats, attacks on western press coverage of the accident, and, on Friday, a visit to the Chernobyl area by Premier Nikolai Ryzhkov and Yegor Ligachev, the second-ranking Politburo member.

On the same day, in West Germany, visiting Moscow party chief Boris Yeltsin provided the first information about what caused the incident and what was being done to remedy the situation.

As the week wore on, the sparse reports began to take the tone of daily briefings, providing limited, but more interesting, information. A Tuesday report of the dead and injured was updated Thursday, saying that 18 of the 148 still hospitalized were in serious condition.

And yet, even these efforts -- extensive compared to the Kremlin's previous approach to domestic disasters -- left western diplomats here more irked and worried than relieved.

Wednesday and Thursday, in meetings with envoys from Finland, the Netherlands, Britain and Austria, Soviet officials said little more than Tass, the diplomats later reported. They avoided explanations on how the situation occurred, or how high radiation levels had been, the diplomats said. "They even denied that there was a fire," one said.

The Soviet Foreign Ministry and nuclear officials also apparently failed in their attempts to convince the western envoys that the Chernobyl situation was safe. Following the meetings, all but one of the western countries with citizens in the area proceeded with evacuations. Only West German workers remained.

As the problem in the Ukraine enters its second week, western diplomats have begun to press with questions about who or what caused the explosion and fire.

So far, officials in Moscow have shunned even perfunctory responsibility for information on the affair. When the Dutch envoy here sought to deliver a letter on behalf of the European Community, he was told that the Atomic Energy Commission, not the Foreign Ministry, was the responsible body. In the end, he met with a committee of officials from both.

As party chief for the republic in which Chernobyl is located, Shcherbitsky bears ultimate responsibility for the safety maintenance of Ukrainian nuclear facilities, and for the handling of public disasters in the area, according to Soviet officials.

He already has been implicitly criticized for the lagging cleanup efforts there. A Tass dispatch today said that "decisions were taken on additional measures to expedite work" after the visit of Kremlin leaders Ryzhkov and Ligachev.

"The implication," one western analyst said, "is that the initial measures were considered inadequate."

If a delay in the reporting of the accident to senior Kremlin officials did occur, Shcherbitsky is likely to shoulder blame for that, too, western analysts said.