MANAGUA, Nicaragua (AP) _ President Violeta Chamorro condemned the slaying of a former Contra leader and said it threatened the stability of the nation, still torn by bitter politics on the left and the right.

''This brutal and senseless crime merits repudiation by the government and citizens in general,'' Mrs. Chamorro said Monday in a message from Czechoslovakia, where she is holding talks with officials.

Enrique Bermudez, 58, was gunned down on Saturday outside a downtown hotel. No group has claimed responsibility for the assassination. Conservatives blamed the killing on leftist Sandinistas, who said they were blameless.

Conservatives questioned the commitment of the Chamorro administration to protect the Contras. The rebels laid down their weapons last year after waging a nine-year, U.S.-backed war against the former Sandinista government.

The Contras backed Mrs. Chamorro's presidential campaign and after taking office in April, she promised the 20,000-strong rebel force land, protection and other benefits in return for peace.

Mrs. Chamorro said Monday that the Bermudez slaying ''constitutes an attack on national reconciliation and the stability of the country.''

She named several officials to head a delegation accompanying the Bermudez family to Miami for funeral services.

Elsa Bermudez said her husband would be buried in Miami because ''I want to feel tranquil at his tomb, to cry there. I'm not coming here to visit it.''

Bermudez was a colonel in the National Guard that supported former dictator Anastasio Somoza and was Nicaragua's military attache in Washington when Somoza was ousted by the Sandinista revolution in 1979.

He left Nicaragua to live for years in Miami but returned in October.

Officials said they had no suspects in Bermudez's slaying. The right-wing Radio Corporacion blamed the Sandinistas.

The Sandinistas say they had nothing to do with the murder. Sandinista Radio Ya has attacked Bermudez as a warmonger responsible for the death and suffering of many Nicaraguans.

Some former Contras have described Bermudez as corrupt and guilty of human rights abuses. Several rebel commanders quit to protest Bermudez's joining the seven-man, Miami-based Contra directorate in 1988.

Last week, the pro-Sandinista newspaper El Nuevo Diario charged that Bermudez met with 80 former Contras about organizing a new underground fighting force.

Nicaraguans remain polarized after years of civil war, despite efforts by Mrs. Chamorro and Sandinista leaders to reconcile their differences.