The Nicaraguan government said today that Honduran Air Force planes attacked and sank a Nicaraguan Navy patrol boat in the Caribbean, and the two governments exchanged accusations in one of the most serious bilateral incidents of the past year.

Nicaraguan Foreign Minister Miguel D'Escoto, in an official protest, said one Nicaraguan sailor was dead, another missing and four injured after a Nicaraguan Navy boat was attacked by three Honduran aircraft while chasing an unidentified "pirate" craft near the Edinburgh Keys in Nicaraguan waters about 4 p.m. Wednesday.

The Honduran government confirmed that its aircraft had attacked and seriously damaged the craft but insisted that the incident had taken place in Honduran waters and that the Nicaraguan patrol boat had been chasing an unarmed Honduran fishing boat.

In Honduras, the Foreign Ministry released a letter from Foreign Minister Edgardo Paz Barnica that said the Nicaraguan boat was about 20 miles north of Cape Gracia a Dios, in Honduran waters, when it "harassed" a Honduran fishing boat. The Honduran boat radioed for help, and the Honduran planes "proceeded to repel the attack that the national boat was sustaining, causing grave damage to the attacking coastal patrol boat," the Honduran letter said.

"My government presents its most energetic protest for this new incursion into national territory, this time by sea, as well as the manifestly hostile attitude of the Nicaraguan government," Paz Barnica's letter said.

D'Escoto, in his protest letter to the Honduran foreign minister, insisted that the incident was directly related to the debate in Washington over President Reagan's request that Congress renew funding to Nicaraguan rebels, most of whom operate out of Honduras.

"These events appear to have the objective of creating artificial conflicts with Nicaragua in order to gain the support of the Congress for President Reagan so he can continue his immoral and brutal war of aggression against Nicaragua," said D'Escoto.

D'Escoto said the incident was also an attempt to divert the attention of Honduras from its constitutional crisis, an internal political dispute between President Roberto Suazo Cordova and the Honduran Congress that has resulted in the imprisonment of a Supreme Court justice.

Although accusations of border violations and violations of territorial waters were exchanged frequently during 1982 and 1983, the past year has seen few such exchanges.

Last May, a Honduran Air Force helicopter was shot down over Nicaraguan territory and eight Hondurans died. The Honduran government later said the aircraft had flown over Nicaragua by mistake.

In January of last year, a U.S. Army helicopter was shot down as it overflew Nicaragua near the Honduran border. The aircraft crashed just across the border in Honduras and its American pilot was killed by Sandinista fire.

The Caribbean coast, especially near the Nicaraguan-Honduran border, has also been the scene of incidents in the past. The Sandinista government says its fishing boats have been attacked by anti-Sandinista rebels and also by Honduran patrol boats, costing Nicaragua's fishing industry millions of dollars in losses. The Nicaraguans have converted some fishing boats into military patrol boats to guard its northeastern coast.

D'Escoto also said that events such as Wednesday's could affect peace-making efforts currently under way under the auspices of the Contadora group -- Mexico, Colombia, Venezuela and Panama -- but he did not elaborate.