Special to The New York Times

HAVANA, June 28--Twenty-four men of the United States Navy base at Guantanamo Bay, in eastern Cuba, are missing.  A United States spokesman here said he believed they had been kidnapped by the Cuban rebels led by Fidel Castro.

The men, all Navy and Marine Corps personnel on overnight leave, disappeared last night between the inland town of Guantanamo and Caimanera on the bay twenty miles farther south, where the base is located.

The bus in which the men had been traveling was found empty this afternoon at a point about thirty miles east of the base.  It had been spotted from the air earlier in the day.

The driver and the conductor of the bus, both Cubans, also are missing.

In Washington, a Navy spokesman said the bus had left Guantanamo at 9:25 P.M., Friday.  He added that three shore patrolmen were among the missing men.

Officials assumed that the sailors and marines had been seized in retaliation against alleged United States aid to the Cuban Government.

These developments occurred as a United States consul left Santiago de Cuba, on orders of Ambassador Earl E. T. Smith, to make contact in the near-by hills with the rebels who had kidnapped ten Americans and two Canadians Thursday night.

An American Embassy spokesman said the consul, Park Wollam, had set out this afternoon with Balfour Darnell, construction manager of the Moa Bay Mining Company.

The twelve, technical and supervisory personnel, had been taken from company properties on the north coast of the Oriente Province, center of the Castro revolutionary activity against the regime of President Fulgencio Batista.

A Cuban chauffeur, so far unidentified, who was in some manner carried off with the twelve kidnapped, technicians, returned to Moa Bay today, according to the embassy.

The chauffeur said he had been released by the rebels and sent back.  He said the kidnapped Americans and Canadians "were well and unharmed" and that in his opinion "they would be released very shortly."

Consul Wollam is following instructions of the United States Ambassador, Earl E. T. Smith, to get "in direct contact with the rebels and arrange the release of the Americans and Canadians."

Ambassador Smith explained this afternoon that when he originally told the consul not to make contact with the rebels directly, he did not have sufficient information on the situation.  Now, having received the report of the consul, the Ambassador has instructed Consul Wollam to carry out the negotiations directly with the rebels.

Ambassador Smith has sent the second secretary of the embassy, William Bowdler, to the United States Guantanamo naval base to serve as a source of communications between Moa Bay and the embassy, Moa Bay has no telephone service and the only communication is maintained by radio through as hip anchored in Moa Bay.

The twelve kidnapped men are chemical and supervisory personnel employed by the Moa Bay Mining Company.

The Moa Bay company properties are on the north coast of Oriente Province, the center of Fidel Castro's revolutionary activity against the Government of Fulgencio Bastista.

Two hundred rebels invaded the Moa Bay company properties and carried off the twelve men, the rebels said, in retaliation for the provisioning of Cuban Army planes by the United States Naval Base at Guantanamo with bombs and gasoline for attacks of Oriente Province.

They said such provisioning violated the hemispheric defense pact, which they said provided that the United States may supply arms to Latin-American countries only for defense against non hemispheric enemies.

Meanwhile Camp Colombia Army Headquarters in Havana issued a statement that said: "A small group of Communists headed by Raoul Castro kidnapped various American officials of the Moa Bay company.  A small detachment of the Cuban Army stationed nearby pursued the bandits and killed several of them.  The pursuit is continuing carefully to prevent the injury to any of the kidnapped men.  It is expected that this group of bandits will be captured soon.

On March 30 rebels under the command of another Fidel Castro lieutenant seized the Moa Bay properties and remained in control of them for fourteen hours.  The small Cuban Army garrison took refuge on a navy boat in the bay.

The group that kidnapped the Americans and Canadians also seized nineteen vehicles, hospital supplies and a number of beds.

In Havana, one youthful revolutionist was killed and one seriously wounded this afternoon in a gun battle with the police.  The police were said to have learned that a group of the 26th of July revolutionary movement in an apartment led by Senor Castro were meeting in an apartment in the Santo Suarez section and surrounded the building.  A hand grenade thrown by one of the youths wounded a police sergeant.

WASHINGTON, Sunday, June 29 (AP)--The Navy Department early today issued the following statement on the disappearance of the Guantanamo personnel:

"A bus manned by a Cuban civilian crew consisting of driver and conductor departed Guantanamo City Friday evening 9:25 P.M. with twenty-four Navy and Marine Corps personnel on board, including three shore patrolmen."

"It was bound for the naval base Guantanamo.  It failed to arrive.  Saturday afternoon the bus was found empty about thirty miles east of the naval base."

OTTAWA, June 28 (UPI)--The Canadian Government has told the Government of Cuba that it wants the two Canadians kidnapped by the rebels returned to safety "immediately and unharmed," Under Secretary of State Jules Leger said today.

As yet, no official reply has been received from the Cuban authorities, Mr. Leger added.

The two Canadians, both working for a United States mining company, have been identified as Harold G. Kristjanson, 37, of Winnipeg and Edward Cannon, 50, of Cornwall, Ont.

Mr. Leger said that Canada did not plan to negotiate directly with the rebels for their return.  The United States announced today that it would follow such a course to obtain the return of all the captives.