For the second time in two months, a significant initiative by West Germany to improve East-West relations has fallen apart, with the cancellation by Foreign Minister Hans-Dietrich Genscher of an official visit to Poland only hours ahead of his scheduled departure for Warsaw today.

The Foreign Ministry in Bonn announced early today that in the final stage of preparing the trip "circumstances had arisen which required it to be postponed in the interests of reconciliation and normalization."

For the government of Chancellor Helmut Kohl, the cancellation dealt another blow to its campaign to enhance channels of cooperation between countries in the eastern and western blocs during a prolonged phase of chilly relations between the United States and the Soviet Union.

Two months ago, East German head of state Erich Honecker and Bulgarian leader Todor Zhivkov bowed to apparent Soviet pressure and called off scheduled visits to West Germany.

The Honecker trip would have served as a potent symbol of the improving ties earlier this year between the two German states. This rapprochement evoked suspicion and concern in Poland, Czechoslovakia and the Soviet Union, which have waged a fierce press campaign accusing Bonn of trying to incorporate East Bloc territories into a greater, reunited Germany.

West German officials admitted that such setbacks showed the limited scope for smaller countries within the two blocs to improve their relations while Moscow and Washington remain at loggerheads.

"There is only so far you can go before realizing that the road to meaningful and lasting detente with the East Bloc states passes through Moscow," an East-West specialist in Bonn said.

West Germany's efforts to bolster contacts with Eastern Europe have also been complicated by persistent cases of asylum seekers intent on emigrating from the East Bloc.

West German embassies in Prague, Warsaw, Budapest and Bucharest are still occupied by more than 100 East Germans, or local citizens of German origin, who are demanding exit visas to the West.

In addition, 192 Poles traveling on the liner Stefan Batory jumped ship in Hamburg Monday with the apparent intention of seeking asylum and settling in the West. On Friday, another group of 93 Poles reportedly fled their ship in Travemuende.

While the asylum controversies have complicated relations with the East Bloc, West German Foreign Ministry officials insisted today that the Polish refugees did not have anything to do with the decision to put off Genscher's trip.

For Poland, which today voiced the hope that the visit would take place in the future, the postponement represents a major setback to hopes of significant improvement in relations with Western Europe after three years of diplomatic isolation, Washington Post correspondent Bradley Graham reported.

Despite the cancellation, Kohl stressed today that his government would continue its efforts to restore detente and pursue enhanced relations with East Bloc countries.

"Although the present reaction of the Polish government is incomprehensible, we shall continue on our course," Kohl said at a press conference in Vienna. "The road to reconciliation is the only right one."

Earlier today, Foreign Ministry spokesman Juergen Chrobog cited three conditions that had prompted the cancellation, including a "public admonition" by Polish authorities to Genscher warning him not to lay a wreath at the grave of pro-Solidarity priest Jerzy Popieluszko, who was killed by three Polish security police officers apparently for political reasons.

Genscher was also told he would not be allowed to lay flowers at the grave of an unknown German soldier in a Warsaw cemetery or bring along a West German journalist accused of insulting Polish leader Gen. Wojciech Jaruzelski.

In Warsaw, a senior Polish Foreign Ministry official, Wladyslaw Klaczynski, said the reasons given by Bonn were unconvincing. He added that "the road toward improving Polish-West German relations is still open," correspondent Graham reported.

The issue of Warsaw's objections to Genscher laying a wreath at Popieluszko's grave raised doubts in Poland about upcoming visits by the foreign ministers of Italy and Denmark, who also are likely to want to pay tribute to the slain priest, Graham added.

Kohl expressed chagrin today over "unfriendly remarks" by Polish officials at a time when West Germany has "continually urged our allies to show more sympathy for Poland."

It has done so in the belief that such overtures would encourage more conciliatory policies by the Jaruzelski government.

Genscher, who still intends to visit Prague next month and Budapest early next year, would have become the first NATO foreign minister to visit Poland since martial law was declared three years ago.

The warning not to visit the grave of Popieluszko appeared to be a strong signal that hard-liners in the Polish government were adamant about blocking any gestures of support for the political opposition by visiting western dignitaries.

Earlier this month, British diplomat Malcolm Rifkind, who is in charge of East-West relations at the Foreign Office in London, laid a wreath at Popieluszko's grave and also held talks with opposition figures.

Diplomats in Bonn said the Polish government may have decided that any possible economic benefits that might derive from an opening to the West were not worth the political risks of reviving the suppressed Solidarity movement.

West German officials said that Genscher had no intention of insisting on a visit to the Popieluszko grave if the Polish government did not create a public confrontation over the issue. But the admonition voiced by the Polish government spokesman, Jerzy Urban, at a press conference yesterday, "made it impossible for us to go ahead . . . ," a Foreign Ministry source said.

Genscher intended to make a conciliatory speech on the closing day of his visit about the need to rebuild detente and bury the hostility of the past. But the Polish government wanted him to renounce any territorial claims by West Germany, a statement that Genscher felt would be redundant and humiliating, officials in Bonn said.

Graham added from Warsaw:

Some Poles and western diplomats in Warsaw speculated that the Polish leadership may have wanted the trip put off in view of resurgent opposition activity here following Popieluszko's death and signs of an internal Communist Party struggle.

In support of this, it was noted that recent visits by government figures from Greece, Finland, Austria and Britain had yielded little in the way of tangible benefits for the Polish government -- particularly no immediate economic assistance.

In the case of Rifkind, the visit brought political embarrassment. By meeting with four dissidents and laying a wreath at Popieluszko's grave, Rifkind set a precedent other western officials could feel obliged to follow.