Special to The New York Times
HAVANA, April 15 - Intensified action by the Government forces in Oriente Province and the loss of arms is weakening the Cuban insurgents, according to reliable sources.

In Havana, members of the revolutionary organization headed by Fidel Castro and of other anti-Government groups sought to reorganize their forces following an attempted general strike last Wednesday. The strike was to have been their supreme effort to overthrow the regime of President Fulgencio Batista.

The reorganization went on surreptitiously while the police and military intelligence services hunted the rebels down through every secret agent they could muster. The Chief of the National Police Brig. Gen. Pilar Garcia, said yesterday that “the police stations are full of prisoners.”

According to the Constitution, prisoners should be delivered to the courts within seventy-two hours, but with constitutional guarantees suspended and a “state of national emergency” in effect, the military forces can keep prisoners in jail for an indefinite period without making any charge against them.

In Pinar del Rio Province a small vessel attempting to land a shipment of arms for rebel forced in western Cuba was captured and four of the expedition members were killed, according to a statement issued late last night by army headquarters here.

The army had learned of the landing in advance and troops surprised the group as it came ashore from the small vessel El Corojo, headquarters said. The entire shipment of ninety rifles, two radio transmitters, thirty-eight automatic pistols, anti- tank guns, four machine guns, cases of dynamite, phosphorus and ammunition, food supplies and uniforms of was captured, headquarters said. The 26th of July Movement, led by Señor Castro, takes its name from the date of an anti- Batista uprising in 1953.

Censorship was tightened in Havana despite the apparent advantage gained by the Government over the rebels. Foreign correspondents, who had been assured by Premier Gonzalo Guell at a special news conference that they might send their dispatches abroad without difficulty, found themselves cut off by censors on the telephone, which normally is the most rapid method of sending messages abroad.

The censor said that in future only official announcements could be transmitted in accord with an order issued by the Minister of Interior. An inquiry at the office of the Premier indicated that this had caught Dr. Guell by surprise. This afternoon he said: “There has been no change of policy about the dispatches of foreign correspondents.”

Army headquarters said tonight that government troops and rebel units were engaged in heavy fighting near the United States Navy’s base at Guantanamo in Oriente Province. The rebels were said to be retreating.

"Army operations are satisfactory and the army will soon dominate the situation," headquarters said.  The army is throwing its full strength from Guantanamo to Niquero, about 150 miles to the east, the communiqué added.

BUENOS AIRES, April 15 (Reuters)--Supporters of Fidel Castro raided the Cuban Embassy here today.  They held Ambassador Alberto Espinosa Bravo and his staff at gunpoint and then make off with a large haul of passports and official papers.