MANAGUA, NICARAGUA, JAN. 6 -- El Salvador has charged that the Salvadoran guerrillas' general military command is currently located in a building near Managua's international airport, Latin American diplomats said today.

El Salvador's accusation that Nicaragua violated a regional peace plan by continuing to aid the Salvadoran rebels came during the 36-hour visit here of a 15-member international commission monitoring the progress of the peace accord. It was signed Aug. 7 in Guatemala.

This was the first time since the signing that El Salvador's Christian Democratic government carried out its threat to provide specific details of sites in Nicaragua where the rebels allegedly maintain military command centers and communications facilities.

Since the verification commission began its first tour through Central America on Sunday, it has heard a string of hostile charges from governments. The commission, composed of representatives from the United Nations, the Organization of American States, and 13 Latin American nations, is preparing a report to be presented to the Central American presidents when they meet in Costa Rica Jan. 15 to assess progress under the accord.

"Now the hour of the accusations has arrived," commented one verification commission member.

El Salvador's allegations came in the form of an anonymous question posed by a United Nations delegate on the verification commission to Nicaraguan Vice President Sergio Ramirez during a closed-door session yesterday, according to diplomats who were present.

The Salvadoran government claimed that the general command of the rebel Farabundo Marti National Liberation Front (FMLN) is housed in the 32-22 House, a Sandinista military installation just off the major highway past the airport east of Managua, the sources said.

It also charged that a propaganda office and printing press are in a half-crumbled building in Managua's earthquake-ravaged downtown, within walking distance of President Daniel Ortega's offices, according to the sources. It said the FMLN maintains a training and operations base near the northwestern port of Realejo, at Estero Caballo.

El Salvador further claimed that Sandinista Army Battalion 30-11 is training guerrilla fighters at its garrison, and that the FMLN and its political allies maintain a "logistics center" at Kilometer 10 1/2 on the highway south of Managua.

El Salvador said it detected seven arms deliveries from Nicaragua to its territory in September, mainly supplying automatic rifles. It listed the names of seaside points where the shipments left Nicaragua and arrived in El Salvador, as well as detailing the map coordinates of the alleged location of a transmitter of the FMLN's Radio Venceremos.

Nicaragua's Ramirez called all the allegations false but did not elaborate.

Nicaragua used the commission meetings to lay out complaints against El Salvador, Costa Rica and Honduras for allegedly continuing their logistical support for the Nicaraguan rebels, known as contras.

During meetings Monday in San Jose, Costa Rica, Nicaraguan representatives outlined routes through Costa Rican airspace used by CIA-run resupply flights for contras fighting in southern Nicaragua. It gave a location in San Jose where two contra military radio transmissions were said to originate.

Today, Nicaragua charged that contras in Costa Rican territory fired an antiaircraft missile last week at a civilian cargo plane belonging to Aeronica, the Nicaraguan state airline, when it was flying low over Costa Rica because of mechanical difficulties.

"These things don't happen in Costa Rica, and if they do it's without the knowledge of the president," said an indignant Costa Rican diplomat. Costa Rican President Oscar Arias was the key author of the Guatemala accord and the 1987 Nobel peace laureate, and since August Nicaragua has refrained from attacking his government.

This morning, Maj. Ricardo Wheelock, head of Sandinista military intelligence, pointed out on a map locations in Honduras where Nicaragua has detected contra airfields, base camps, command posts and CIA-run radio transmission interception centers.

Commander Luis Carrion, the Sandinista vice minister of the interior, said Nicaragua has seen no change in contra activities in Honduras since Aug. 7.

The Honduran representative to the commission, Jorge Hernandez Alcero, admitted only that contra fighters "enter and leave Honduran territory as a product of the civil war they are fighting in Nicaragua."

Hernandez said Honduras will allow the commission to inspect Aguacate, a Honduran military airfield used for contra air supply operations, and Swan Island, in the Caribbean Sea north of Honduras, the contras' CIA-run logistical base.