HAVANA - Cuba's President Fidel Castro announced on Monday he was shunning a World Trade Organization (WTO) summit in Seattle and he accused U.S. authorities of backing a Cuban exile "plot'' to have him arrested on U.S. soil.

The announcement, made in the form of a public letter to a U.S. Democrat congressman who had invited him to the U.S. city, ended days of intense media speculation about the possible participation of the veteran Cuban leader in the WTO meeting.

In the letter addressed to Rep. Jim McDermott of Washington state, Castro cited moves by extreme right-wing Cuban exiles in the United States to have him arrested by U.S. police for ''murder'' once he set foot on U.S. territory.

He made clear that any such attempt to detain him by force in Seattle would have "inevitably'' resulted in a "bloody armed conflict between Cuba and the United States''

Castro bluntly accused the U.S. government of condoning and even supporting the moves to obtain his arrest, which stemmed from a 1996 incident in which a Cuban MiG fighter shot down two small U.S. planes, killing four Cuban exile pilots.

"Without doubt, a plot was being planned against my trip to Seattle with the support of the Department of State,'' Castro said in the 6-page letter, dated on Nov. 29, which was distributed to foreign correspondents in Havana.

The Cuban leader added it was clear to him that the U.S. government did not want him to attend the WTO summit.

He had been widely expected to use the major international event to denounce once again the long-running U.S. economic embargo against communist-ruled Cuba and also to proclaim his well-known opposition to the world capitalist system.

"I was certain the State Department would not grant me the visa. For that reason, I did not even bother to request it. I didn't want to be submitted to that humiliation,'' Castro said.

State Department spokesman James Rubin, who said earlier that the authorities had received no visa request from the Cuban leader, declined to comment on Castro's charge that he had been discouraged from attending the event.

"We've seen reports of his comments. All I can really say is that we processed visa requests for the Cuba delegation efficiently and expeditiously and we would have processed his visa in the same fashion,'' Rubin told Reuters in Washington.

"As for his broader charges, we have no comment,'' he said.

In his letter, the 73-year-old Cuban leader made clear he had been intending to take part in the Seattle summit and had received many requests from institutions and personalities for interviews and speaking appearances.

"I was feverishly preparing for it,'' he said.

Castro added he had read in media reports that his political enemies like Cuban-American congressman Lincoln Diaz Balart and the fiercely anti-communist Miami-based Cuban American National Foundation were seeking his arrest.

They and other Cuban exile opponents accused him of being personally responsible for the 1996 deaths of the four exile pilots shot down over the sea north of Havana.

Castro said he had waited to see the reaction of the U.S. government to these moves to obtain his arrest.

He added that in a meeting with a senior Cuban diplomat in Washington last Friday, State Department officials had warned about this possible outcome of a trip by him to Seattle.

The U.S. officials had used "the same arguments as the Cuban-American extremist mafia'', Castro said. He went on to accuse them of "washing their hands like Pontius Pilate.''

His trip to Seattle would have been a rare foray by the Cuban president into the heart of a nation whose political system he reviles as the epitome of "imperialist'' capitalism.

Castro's last visit to the United States since the 1959 Cuban Revolution was to the U.N. in New York, in 1995.

The Cuban president said Foreign Minister Felipe Perez would lead the Cuban delegation to the WTO meeting. Foreign Trade Minister Ricardo Cabrisas would also take part.

© 1999, Reuters Ltd.