Mikhail Gorbachev accused President Boris Yeltsin on Thursday of trying to intimidate him with the carefully timed release of top-secret documents linking the Soviet Communist Party to the massacre of 21, 000 Polish soldiers during World War II.


The charge was the latest in a bitter public feud between the present and former Kremlin leaders that has seen Gorbachev made a virtual prisoner in Moscow and his research institute's building seized on Yeltsin's orders.


The tangle, which originated with Gorbachev's refusal to testify in the Communist Party court case, has presented Yeltsin with a serious public-relations problem abroad. Numerous countries have protested the withholding of Gorbachev's passport, most recently Italy, where the former president had been due to travelthis week.


In an apparent effort to recapture the public-relations advantage, Yeltsin on Wednesday released secret files showing that the party's top body, the Politburo, had approved the 1940 massacre of Polish soldiers, which was carried out by Soviet troops in and around Katyn forest, near Smolensk.


When he made the documents available, Yeltsin's spokesman, Vyacheslav Kostikov, said that every Soviet leader, including Gorbachev, had actively supported the country's 50-year effort to cover up the massacre, instead blaming the killings on Nazi forces.


Looking worn as he stood before reporters in an open hall of his research institute, the former Soviet president said that he had seen the top-secret file only two days before he resigned last December.


He said that on Dec. 23, 1991, he and his aide, Alexander Yakovlev, had viewed and handed the file over to Yeltsin, urging him to publish it.


"I said to Boris Nikolayevich, it is your time now", he said.


Gorbachev added that the Katyn file was one of 2, 000 top-secret files that had been kept in a large room in the Kremlin, and that the idea that every Soviet leader had been acquainted with all of them was "nonsense".


But Yeltsin's spokesman said Wednesday that Gorbachev saw it earlier. He said documents showed that Gorbachev received the file on April 18, 1989, from his chief of staff, Valery Boldin, who has since been charged for plotting the August 1991 coup against Gorbachev.


Although the file does not bear Gorbachev's signature anywhere, it shows that the Politburo discussed the case annually after 1971, Sergei Shakhrai, Yeltsin's representative at the Constitutional Court, said at a separate news conference.


Shakhrai said that he was sure that Gorbachev, who led the Politburo from 1985-91, knew of the file. Shakhrai also received the documents Wednesday and said he would use them in his defense of Yeltsin's decrees banning the party's activities.


Gorbachev repeated Thursday that, as Kremlin chief, he had not been able to correct all of the Soviet Union's past mistakes at once.


"I conducted myself the way I had to", he said. "There was nothing else I could do".


He said that as Kremlin leader he had approved the admission in April 1990 that the Soviet Union was to blame, for the Katyn massacre.


"Gorbachev started this process anew", he said.


Gorbachev also said that his relations with the chairman of the Constitutional Court hearing the Communist Party case, Valery Zorkin, which he has until now described as cordial, had turned sour in recent days. He said the court was considering suing him for unfavorable comments he had made to the press.


Zorkin took a jab of his own Thursday, accusing Gorbachev of "seeking to play the role of the Great Martyr".


Zorkin told Itar-Tass, however, that the court may withdraw its summons to Gorbachev, describing him as "useless baggage who is not only unable to clear up the truth, but will also try to mislead the court".


Gorbachev also thanked Yeltsin for showing "the mercy of a czar" by lifting the travel ban so that he could attend Willy Brandt's funeral in Germany on Saturday.


He had to cancel his trip to Italy on Wednesday, when he learned that his passport was good only for Germany. Last week he was also forced to postpone a trip to South Korea.


In a statement quoted by Itar-Tass, Prime Minister Giulano Amato of Italy on Thursday expressed his government's surprise and concern over the travel ban, which he said was "incompatible with the process of democratization now underway in Russia".