SAN JOSE, COSTA RICA, JAN. 15 -- Five Central American presidents today opened a summit meeting amid recriminations about compliance with a regional peace accord signed five months ago.

The presidents of Nicaragua, El Salvador, Honduras, Guatemala and Costa Rica gathered at the Central American Institute of Business Administration, located in the countryside north of the Costa Rican capital, to evaluate the peace plan they endorsed Aug. 7 in Guatemala.

The meeting is being watched in Washington because Congress is scheduled to vote early next month on whether to continue aid to the rebels fighting to overthrow Nicaragua's leftist government, one of the conflicts that the peace plan is intended to stop.

Honduran and Salvadoran officials charged before going into the meeting that Nicaragua's Sandinista government had not complied with the peace accord's provisions, and they firmly rejected the idea of setting a new timetable that would again extend the deadline for compliance.

The plan originally set a Nov. 5 limit for the five countries to implement amnesties, cease-fires, democratization, the cessation of outside aid to rebel forces and a ban against using one state's territory to attack another.

Nicaraguan President Daniel Ortega said the Salvadoran and Honduran statements were "not constructive" and called on the two countries' presidents to explain the recent murders of human rights officials in each country.

Ortega mentioned the assassination in October of Herberth Anaya, the head of a human rights group in El Salvador, and the murder last night in Honduras of Miguel Angel Pavon, the vice president of the independent Honduran Committee for Human Rights.

Salvadoran President Jose Napoleon Duarte has charged that leftist guerrillas killed Anaya and has presented an alleged participant who testified to that effect.

The murder last night of Pavon in the Honduran city of San Pedro Sula came a few days after he had testified to the International Commission on Verification and Follow-up on Honduran compliance with the peace accord, Ortega said.

Pavon also had been the first witness to testify in a case before the Inter-American Court of Human Rights concerning the disappearance of four people allegedly killed by Honduran military death squads in 1981 and 1982. According to the human rights group Americas Watch, he is the second witness in the case to be killed in the past two weeks.

In a news conference, Ortega insisted that the summit deal seriously with a verification commission report that calls for a halt to U.S. aid for the Nicaraguan rebels, known as contras. The five presidents agreed last August to request an end to contra aid at the same time the peace plan's other provisions took effect.

The verification commission is made up of the foreign ministers of the five Central American countries, plus Mexico, Panama, Colombia, Venezuela, Argentina, Brazil, Uruguay and Peru, and representatives of the United Nations and Organization of American States. Honduras and El Salvador, who are close U.S. allies, have denounced the body as biased in favor of the Sandinistas.

In an interview today before the summit meeting began, Honduran President Jose Azcona said he would not ask the United States to cut off aid to the contras as long as Nicaragua had not fully complied with the peace plan by implementing democratic reforms.

"We haven't done this and we are not going to do it while there is no proof that Nicaragua is going to democratize," Azcona said.

"What do we gain from calling for an end to aid?" he asked. "What does Honduras gain if the entire Nicaraguan Resistance is suspended when there is no internal democratization in Nicaragua that guarantees us that there will be no subversion or guerrillas in Honduras supported by a Marxist government in Nicaragua?"

Azcona said he would not agree to any further postponement of the peace accord's implementation deadline. But he asserted that "this plan should continue." He added, "There are moral obligations that continue. We want to rescue the fate of this document."

Azcona said "Honduras has complied 100 percent" with the peace plan, although he later acknowledged that his government had not allowed investigation of contra activities in Honduras that would violate the agreement. "If some things related to the contras" were found in Honduras, he said, "we would take corrective measures." He did not elaborate.

Contra supply flights to Nicaragua "can leave from many airports," he said in answer to a question. "We are not going to deny that flights have left from Honduras. But it doesn't mean that the contras have control of any airports in Honduras. Maybe some contra flights leave from Mexico."

Azcona criticized the verification commission as "completely biased" in favor of Nicaragua, and he lashed out especially at Mexico and Panama.

"In Honduras there is more freedom of expression than in Mexico and Panama," he said. "It is not the foreign minister of Mexico who can dictate standards to us."

In a separate interview, the Salvadoran defense minister, Gen. Carlos Eugenio Vides Casanova, said the Salvadoran delegation also opposed an extension of the peace plan's deadline. "Nicaragua has already had time enough to comply if they wanted to," he said.

Vides Casanova said he and the defense ministers of Honduras and Guatemala had met this week in Guatemala City to assess the peace accord's progress from a military point of view. He said the three had expressed concern to their respective presidents about Nicaragua's military buildup and urged them to "take this into account" during their summit talks.

The "disproportionate growth" of the Sandinista military indicated that "these are not forces strictly for defense," Vides Casanova said. "We see them as a threat to our security."

In his news conference before the talks began, Ortega called on the five presidents "not to let ourselves be pressured by the United States." He said his Sandinista delegation "came to interpret the Christian sentiment of our people" in the search for peace and not to "get in a boxing ring."

The summit meeting's host, Costa Rican President Oscar Arias, urged his colleagues in an opening speech to resist pressures from unidentified persons who he said were trying to impose their will on the conference.

"If we are not capable of reaching the agreements that history and our peoples demand of us," he warned, "we will have much to lose and nothing to gain."

Ortega's participation in the summit has aroused political passions among Costa Ricans. Groups supporting and opposing the Sandinistas have filled local newspapers with advertisements and today held separate demonstrations in San Jose.

Arias and his family have received a number of anonymous death threats lately, presidential aides reported. They said they suspected rightists opposed to Ortega's presence here.