By Peter Kihss

A passionate, bitter letter from Fidel Castro, leader of the thirteen-month-old insurrection in the mountains of eastern Cuba, has split the Cuban political opposition to President Fulgencio Batista.

Senor Castro repudiated that Council of Liberation set up last Nov. 1 in Miami in the name of seven opposition groups.  His movement's departure from the Council this week has been followed by the withdrawal of the Orthodoxal party of Dr. Roberto Agramonte and Dr. Manuel Bisbe.

The Miami Council was thus left primarily with the Authentic party forces around former President Carlos Prio Socarras.  Late yesterday, Dr. Manuel Varona, the Council's president, said it was "not functioning" as a result of the walkouts.

Castro Urged to Reconsider

But Dr. Varona said the Authentic party was sending a letter to Senor Castro containing arguments for unity and asking him to reconsider "on behalf of the country's present necessity and future stability."

In addition, he said, the Authentic party has decided to accept Senor Castro's proposed candidate for president, Dr. Manuel Urrutia Lleo, a former judge in Oriente Province, Dr. Agramonte revealed yesterday that Dr. Urrutia was first proposed last November by the Orthodox group.

The Council first started work Dec. 24 on a list of five candidates, from which, under earlier opposition plans, civic organizations in Cuba would jointly pick a Provisional President.  But, the majority then left Dr. Urrutia off the list, and he had had only Orthodox and Castro votes.
 
The Council, Dr. Varona said, at that time agreed on four other names.  These were Dr. Felipe Pazos, former president of the National Bank of Cuba, a Castro representative; Dr. Jose Miro Cardona, president of the Cuban Lawyers' Association; Dr. Raul de Velasco, president of the Cuban Medical Association, and Dr. Rafael Garcia Barcenas, Professor of Philosophy at the University of Havana.

Letter Made Available

The splintering of the opposition became known with the availability of the text of a thirty-four-page handwritten letter sent by Senor Castro from the Sierra Maestra Dec. 14 on behalf of his party's directorate.  Addressed to the six other groups, it reached Miami Monday.

Senor Castro asserted his 26th of July Movement was alone carrying on the entire revolutionary struggle inside Cuba while "other compatriots, having had all means, have denied systematically, not to say criminally, all aid."

The letter hinted that some of the opposition might be "in shameful deals" with the Dominican Republic dictatorship of Generalissmo Rafael L. Trujillo.  It also implied that the Miami groups had attempted "to tell us from afar what peak we ought to take, what cane we should burn, what sabotage we should realize" and how to organize a general strike.

In Miami, Dr. Mario Llerena, chief Castro representative abroad, held that the split would help the Castro cause.