HAVANA, March 10-- President Fulgencio Batista said today that Fidel Castro, a rebel leader in the Sierra Maestra was an "agent of the Soviet Union."

    "There is no doubt that the movement headed by Castro is Communist and is aided by communism" the President said.

    He spoke to an armed forces gathering honoring him with a luncheon at Camp Columbia, Army headquarters, on the occasion of the fifth anniversary of the seizure of power by Señor Batista.  Radio and television carried his words throughout the island.

    The alleged participation of Señor Castro as one of the leftist leaders in the disorders in Bogota, Columbia, in April, 1948; his contact with meetings held behind the Iron Curtain, and the dialectics of all proclamations of the rebel movement prove, according to the President, that the rebel leader is a Communist agent.

    Señor Batista assured the people that the rebels had been reduced to scarcely a dozen men and that the Government considered the movement of no importance.

    He said armed forces formerly fighting the rebels in the Sierra Maestra were now engaged in aiding the people of that district to reconstruct their homes and in furnishing them medical aid and other types of assistance.

    The Cuban President deplored reports and rumors that were attempting to build up Señor Castro as a rebel hero both at home and abroad.  He said a "distinguished newspaperman of a great newspaper" had attributed to Señor Castro "camps with organized rebels" that were completely unfounded.  This apparently was an allusion to Herbert L. Matthews of The New York Times, whose interview with Señor Castro, published Feb. 24, caused a sensation in Cuba.

    Reviewing the five years since he seized power, the President said his Administration had brought excellent economic conditions to the island, reestablished public order, greatly increased foreign and local investments, and given stability to the nation.