SAN JOSE, Costa Rica (AP) _ Nicaraguan rebel leader Adolfo Chamorro was put on a plane back to the United States today, two days after he arrived from Miami, Public Safety Minister Benjamin Piza said.

Chamorro is a leader of the U.S.-backed Revolutionary Democratic Alliance, which is trying to overthrow Nicaragua's leftist government. He was expelled from Costa Rica in February 1985 for making inflammatory statements against Nicaragua, and has been living in Florida.

Piza told reporters Chamorro was sent back to Miami on a commercial flight. He said the deportation was linked solely to Chamorro's illegal entry, and denied reports the Contra leader was trying to smuggle weapons or narcotics into Costa Rica.

Jose Davila, spokesman for the Revolutionary Democratic Alliance, said Chamorro had returned to Costa Rica to participate in political activities, which he would not specify.

Authorities initially said Chamorro was arrested Wednesday after arriving on a commercial flight accompanied by two Cubans and a Costa Rican. But Davila told The Associated Press that Chamorro arrived from Miami with a Cuban in a rented twin-engine plane that landed in Nicoya, about 110 miles from San Jose.

The Cuban had been planning to fly to Costa Rica and agreed to take Chamorro as a passenger, Davila said.

Chamorro originally was ordered to leave Costa Rica after a news conference in which he denounced Nicaragua's Sandinista government and announced he was collecting money to support the Contras.

Costa Rican officials said Chamorro's statements endangered their nation's traditional neutrality. Costa Rica has no army.

The Revolutionary Democratic Alliance is one of the smallest of the Contra groups. It is divided by factional squabbles and has made only slight gains in efforts to seize territory in southern Nicaragua along the Costa Rican border.

The group has a small office in San Jose, which the Costa Rican government tolerates as long as it keeps a low profile.

The alliance is not connected with the much larger Nicaraguan Democratic Force, based in Honduras, which operates in northern Nicaragua and also is supported by the United States.