From 1961 until 1974, as Deputy Minister of the Interior, Mr. Pineiro was in charge of the state security apparatus that both protected Fidel Castro and other Cuban leaders from assassination attempts and infiltrated spies into the Cuban exile movement here. In that post, he also supervised the establishment of the internal security organs that monitored and severely punished any sign of domestic opposition to Mr. Castro's rule.  By the mid-1970's, Mr. Pineiro had been placed in charge of the innocuously named Americas division of the international relations department of the Central Committee of the Cuban Communist Party. Unofficially known as the ''Ministry of Revolution,'' that entity supplied arms, money, intelligence, guidance and a rear base to a variety of leftist guerrilla movements in Latin America that wanted to duplicate the Cuban model.  When the Sandinista National Liberation Front overthrew the dictatorship of Anastasio Somoza in Nicaragua in 1979, its leaders privately described as indispensable the role played by Mr. Pineiro, who spent several months in Managua as an adviser to the new Government. A period of intense activity followed into the early 1980's, with Mr. Pineiro helping to organize and direct revolutionary movements in El Salvador, Guatemala, Colombia and Grenada.  In recent years, with a cash-strapped Cuba intent on improving relations with the rest of Latin America in the wake of the collapse of the Soviet bloc, Mr. Pineiro had become somewhat superfluous, and his activities diminished. Officially retired, he became a fixture on the Havana diplomatic party circuit, the luxuriant beard that gave him his nickname now a snowy white.  Diplomats in Havana said today that Mr. Pineiro had attended a reception at the Mexican Embassy on Wednesday and apparently lost control of the car he was driving as he returned home. Though both Cuban and foreign officials today cited unconfirmed accounts that he had suffered a heart attack, the brief official Prensa Latina report announcing his death offered no details, saying merely that he had perished ''as a result of an automobile accident.''  Manuel Pineiro Losada was born on May 14, 1934, the son of the Bacardi rum representative in the province of Matanzas. He had a privileged upbringing, and when it came time for him to enroll in college, his father sent him to study business at Columbia University in New York, where he met and married his first wife, an American ballet dancer named Lorna Burdsall.  But after his return to Cuba, Mr. Pineiro joined Mr. Castro's 26th of July Movement, smuggling arms and supervising urban bomb attacks before he took to the Sierra Maestra to become a guerrilla fighter. He was quickly assigned to the staff of Raul Castro, Mr. Castro's brother, on the eastern front and, according to Mr. Castaneda, ''began building the Cuban intelligence and security apparatus even before the revolution had triumphed.''  The low point of Mr. Pineiro's career, most intelligence experts agree, came in 1967, when Che Guevara was captured and killed in Bolivia while leading a revolutionary insurgency that Mr. Pineiro was supervising and supplying from Havana. As recently as October, as Cuba was commemorating the 30th anniversary of Mr. Guevara's death, Mr. Pineiro was still defending his decision not to send a rescue team to extract the Argentine-born guerrilla hero, with whom he had often disagreed on ideological and strategic questions.  In recent years, Mr. Pineiro continued to cultivate his contacts with his former proteges in the Cuban intelligence and security apparatus and with foreign diplomats, intellectuals and journalists, many of whom remain unconvinced by his assurances that he was then out of the intelligence business. Those who met him in Havana found him to be elegant and cultured, a connoisseur of food, wine, the opposite sex, conversation and literature.  ''He was one of the last of the old hard-liners, a true-blue, unrepentant revolutionary and Fidelista,'' Mr. Anderson said. ''But as a person, he was extraordinarily perceptive, a great raconteur, a roue almost, very personable and blunt, with an endearingly roguish way about him.''  Mr. Pineiro is survived by his wife, the Chilean journalist, writer and Marxist theoretician Marta Harnecker, and a daughter. He was buried this afternoon at Colon Cemetery in Havana with President Castro in attendance and with the full official honors due him as a Commander of the Revolution.
Manuel Pineiro, ruthless but urbane spymaster who for more than 30 years led Cuba's intelligence apparatus and directed its efforts to export revolution to third world, dies in car crash in Havana; photo (M)