Wednesday, March 17, 1999; 2:31 p.m. EST

SANTO DOMINGO, Dominican Republic (AP) -- Former President Juan Bosch, the founder of two of the Dominican Republic's three main parties, is being treated in Cuba for medical problems, party officials confirmed Wednesday.

Bosch, 89, has been suffering frequent nosebleeds. He left for Cuba on Tuesday.

Bosch founded the left-leaning Dominican Revolutionary Party during the rule of former dictator Rafael Leonidas Trujillo. He was elected president in 1962 after Trujillo's death but was toppled by a military coup the following year.

Bosch was defeated in the 1966 presidential elections by Joaquin Balaguer, who subsequently ruled the country with an iron fist for 22 years over the next three decades.

Balaguer has also had health problems and returned from the United States on Feb. 26 after five weeks of treatment for circulatory problems and a lingering case of the flu.

In 1973, Bosch left the Dominican Revolutionary Party and founded the moderate Dominican Liberation Party. He ran unsuccessfully for president on the Liberation Party ticket in 1978, 1982, 1986, 1990 and 1994.

He retired from politics in 1994. In 1996, the Dominican Liberation Party candidate, Leonel Fernandez, was elected president.