Two leading Kremlin officials visited the area of the Chernobyl nuclear disaster yesterday, meeting with people evacuated after the explosion and discussing cleanup efforts, the Soviet news agency Tass reported today.

The senior Kremlin group -- headed by Premier Nikolai Ryzhkov and Yegor Ligachev, the second-ranking official in the ruling Politburo -- made decisions "on additional measures to be taken to expedite the work" of cleaning up after the reactor accident, Tass said, adding that "the work to eliminate the breakdown is being conducted in an organized way."

In other developments, a U.S. bone-marrow specialist began examining radiation victims here today and four U.S. medical specialists arrived from West Germany with Soviet permission to examine potential health hazards of the nuclear accident for Americans based in the Soviet Union.

In Western Europe, thousands of protesters demonstrated to demand the shutdown of nuclear power plants there. Radioactivity levels from airborne fallout from the accident in Chernobyl diminished across most of Eastern and Western Europe, but several countries continued precautionary measures. In Warsaw, a U.S. Environmental Protection Agency official said radiation there now poses no health hazard. Details on Page A30 .

Politburo member Vladimir Shcherbitsky, the party leader of the Ukraine, and several other Soviet officials were included in the delegation of Kremlin visitors, Tass said. The group "visited the area of the Chernobyl power station," according to Tass, but it did not say how close to the site they came.

The Friday visit of two leading Politburo members, reported without pictures tonight on the evening news on state-run television, signals the level of attention the Kremlin is now devoting to the Chernobyl disaster, according to western analysts here.

It coincided with public comments that Boris Yeltsin, leader of the Moscow Communist Party, made about the accident in an interview with West German television yesterday. Yeltsin said "human failure" was probably the cause of the accident "and this we must eliminate." He also said that there is "a dangerous zone" around the plant, 60 miles north of Kiev, because of radioactivity.

Official accounts of the Kremlin delegation's visit today said they had gone to "populated areas," indicating that they apparently had not approached the site itself, which has been evacuated.

Dr. Robert Gale, a prominent U.S. bone-marrow specialist who arrived here yesterday, said he examined some of the radiation victims of the explosion today.

In an interview, he described the cases he saw, which had been brought here from the Ukraine, as serious and "rare but not unknown."

Gale said he plans to travel to the Ukraine to examine other victims, perhaps Sunday.

Tass said Thursday that 18 of the 197 Soviets who were hospitalized following the Chernobyl accident were in serious condition, but today's dispatch gave no further information about them. Earlier, Tass had said that 49 of the 197 had been discharged from the hospital.

Soviet officials have said that two people were killed in the explosion. The official Cuban news agency Prensa Latina said today that it was told by official Soviet sources that the two were reactor workers, The Associated Press reported.

A radiologist and three health physicists attached to U.S. military units in West Germany arrived here today to examine the potential health hazards from the accident for Americans living here. Neither they nor the U.S. Embassy would discuss their activities in detail.

U.S. officials said, however, that the embassy had submitted a detailed list of technical questions to Soviet officials about the incident.

They said they have received no answers.

Meanwhile, Tass and Soviet television continued a growing campaign here against western reaction to the disaster today, with the television featuring street interviews with three Soviets who criticized the western response.

One woman said Soviet television broadcasts showing western officials checking travelers and food exports for radioactivity had provided proof that western reaction to Chernobyl is "a provocation."

A Soviet Army major interviewed also denounced western reaction to the accident and said, "The imperialists will always be looking for any reason, even any fact, to twist it in their own interests."

An engineer who was interviewed by Soviet television said the Soviets had responded with grief when they learned of the Challenger space shuttle accident, but that Americans and others in the West had reacted far differently to a Soviet tragedy.

Tass, in a commentary by Sergei Kulik, charged today that "demanding 'more news' and 'more facts' from Chernobyl, losing all sense of shame and conscience, the politicians are waiting only for bad news," The Associated Press reported.

"It's unlikely that the reports that the situation in the area of the atomic station is normalizing will sober them up," the commentary said, claiming that "the White House and its allies need this witch dance to cast a shadow on the Soviet Union and its peaceful initiatives."

In the past few days, Soviet criticism of western treatment of the Chernobyl incident has loomed larger than official coverage of the incident itself.

United Press International reported the following:

Six weeks before the Chernobyl nuclear disaster, the newspaper Pravda Ukrainy complained of a breakdown in deliveries to the site that could lead to "disorder that is inadmissible at a nuclear power station," according to a translation of the March 18 article in the Ukrainian Communist Party paper by the U.S. Foreign Broadcast Information Service in Washington.

The description of an installation plagued by disorganization, supply problems and inefficiency was reinforced later by a front-page report on March 27 in Literaturna Ukraina, another official newspaper published in Kiev.