Bands of youths are reported to be roving the streets in most major cities, intimidating the people and aiding the secret police in round-ups of suspicious persons. Lists of "suspicious elements" are also being drawn up.

According to diplomatic advices and reports from Cubans living at the eastern end of the island boys and girls in Havana have been armed for police and sentry work. Some of them are only 13 years old.

All indications are that the tight control over all citizens, information and transportation is preventing any popular expression of sympathy for the attackers now battling the Castro forces.

Uprisings Are Key

The Castro Government appears to agree with the insurgents, who have been insisting for months that their cause cannot succeed unless it ignites popular uprising throughout Cuba.

Western Diplomats in Havana said in telephone conversations with this United States base in Cuba that they had no way to judge developments. They said that they could not tell which side was winning and that they did not have much reliable information on military activity.

But they depicted the mood of the capital as extremely tense. Streets are deserted and many Cubans still go to their jobs. But they hurry home and bolt the doors.

Many apparently fear informers in their neighborhoods and have moved in with friends. At the other end of the island, in the cities of Santiago and Guantanamo near this base, the picture is the same.

Many of the 3,500 Cuban employees at this base were reluctant to discuss events even within the safety of the well patrolled fence. They said they minded their own business and just stayed quietly at home each evening.

They said armed youths were roving the streets of Guantanamo checking identification papers and otherwise inquiring into every person's affairs.

The youths search homes at will, apparently looking for literature and other signs of disloyalty to Premier Castro. Hundreds of priests are said to be among the suspects throughout Oriente Province.

Churches Are Searched

Schoolrooms, parish homes and churches also have been invaded repeatedly by youths in search of "evidence of counter-revolutionary activity."

This evening one diplomatic source in Havana said cable communications between his embassy and his home office in the Western Hemisphere had been restored. He said the Cuban Government was making every effort in this and other ways to maintain an appearance of "normality."

Diplomats in general have had only minor difficulties in the last few days, the official said. He said there was no evidence of major sabotage and he denied rumors that the Havana Libre, a Hilton hotel, had been set afire.

Control of the civilian population has been assigned to local committees of defense. The Government-controlled newspaper in Oriente Province, Sierra Maestra, said the committees would have "a list of the enemies for the moment in which they are ordered to pursue them."

Castro Limits News

The Castro Government has forbidden all local radio stations to give any news or commentary not composed at Castro headquarters. Whenever there is an announcement or analysis to be made, all stations join in the network. The rest of the time they transmit their regular programs.

Four foreign newsmen have been forbidden to leave Havana under threat of imprisonment. At least four other United States correspondents have been imprisoned. One has taken refuge in an embassy and one is in hiding from the Castro police.

Robert Perrez, an American who is a part-time representative of The London Daily Telegraph, and R. Hart Phillips of The New York Times have been allowed to remain free, but they have not been permitted to send any news out of Cuba.

Henry Raymont of United Press International was seized at 4 A.M. Monday. His assistant, Martin Housman, is also under arrest.

Jay Mallin, representative of Time magazine, was believed to be in jail. Robert Berrelez of the Associated Press is reported under arrest.