The Reagan administration is seeking to use several dozen U.S. military advisers to train rebels fighting Nicaragua's leftist government, U.S. officials said in interviews this week. This would mark the first direct public involvement of U.S. military personnel with the anti-Sandinista forces.

The program would be similar in scope to the four-year-old training effort by 55 U.S. Army Special Forces advisers with government troops in El Salvador, an administration official said. Schooling in the basics of guerrilla warfare for the Nicaraguan rebels, known as contras or counterrevolutionaries, could take place in their base camps in Honduras, in El Salvador or at military bases in the United States, he said.

The training program will be one of the administration's priorities if it gains congressional approval for $100 million in military and "nonlethal" aid for the contras. The CIA helped organize and train the contras from their inception in early 1982 until Congress cut off military aid and barred further CIA involvement in mid-1984.

The House voted down a proposal for new military aid for the contras on March 20, while the Senate approved a bill for the $100 million on March 27. The White House is expected to go back to the House with a revised proposal after the Easter recess.

In a mid-March interview, Gen. John R. Galvin, the top U.S. commander in Central America, said the contras need to improve their logistics and tactics. U.S. military personnel, he added, have the right skills for "maybe doing a little training somewhere" with the contras.

President Reagan has also referred to his administration's intention to improve the contras' training, and the bill approved by the Senate contains general references to a training program. But the discussion this week by administration officials, responding to questions, provided the first full description of what the aid program would look like.

An official said the administration views training for the contras by the Special Forces, also known as Green Berets, as a way to counterbalance assistance Sandinista infantry soldiers are said to receive from Cuban military advisers, now estimated by the State Department to number 3,500 in Nicaragua.

The administration is waiting to make sure the aid bill passes Congress before settling on sites for the training.

"The problem is that there's no 'contralandia,' " the official noted. "You're talking about training in territory someone else claims."

He suggested some specialized courses could be given to contra volunteers at military bases in the United States. El Salvador, he said, is "certainly a possibility," because Salvadoran officials have been "as helpful as they can be" with recent contra aid operations.

According to diplomats in Central America, private cargo planes on contract to the State Department began last December to ship nonlethal supplies to the contras through the Salvadoran Air Force's Ilopango base in San Salvador. At the time, the government of Honduras was blocking the shipments at its major commercial and military airports. From San Salvador the goods were flown directly to contra bases in Honduras.

It remains unclear whether Honduras, which has recently taken steps toward a new foreign policy that it says will be more independent from the United States, would allow contra training to take place openly in its territory outside the rebel base camps.

The administration hopes to get "a few dozen" Green Berets for the program, an official said, and they would operate under the same kind of restrictions as the advisers in El Salvador. They would not be allowed to go into combat or to cross into Nicaragua with the rebels.

"We would have the same understanding that the officers have in El Salvador," he said. "They realize they might end up coming under fire sometime. There's always some risk."

The proposed training would be an open-ended, "ongoing thing," the official said, and could produce quick results in improving the contras' morale and performance in battle in Nicaragua. But one retired U.S. military commander with extensive experience in Central America recently estimated it could take up to two years to forge the contras' estimated 15,000 fighters into units that could present a challenge to the Sandinistas' forces of 119,000, including militias and reserves.

Many administration officials remain confident that the contras are growing into an insurgency to be reckoned with, and attribute their lack of conspicuous battlefield triumphs in the past seven months to logistical and supply bottlenecks in Honduras and Nicaragua.

"They are just at the point where additional assistance plus advice and training can very quickly turn them into a fighting force that can have a major impact," said one administration official.

"Think of the Salvadoran Army as a parallel," said another. "The contras are where the Salvadoran Army was five years ago." U.S. training of Salvadoran regulars is widely credited with improving their willingness to fight and their counterinsurgency skills.

Congressional opponents of the aid have argued that the contras are proving to be an incompetent, lackadaisical and sometimes brutal guerrilla force.

Another White House priority for the $100 million package is to gain new authorization for the CIA to get back into contra training and operations. Some administration officials would like to see most contra training done covertly by the CIA, instead of openly by the Pentagon.

The bill that passed the Senate contains language to authorize the CIA to use its contigency funds for covert contra operations and does not impose special restrictions on the CIA's role with the contras.

"They want to put us back in strategic control of their operations," said one congressional source. "They want to put our people next to [contra chief] Enrique Bermudez and tell him what to do."

Officials at the State Department, which has been running the nonlethal aid program, are eager to see some of it returned to a covert status.

"This is obviously no way to run a war," said one official. "There are certain areas which require confidentiality."

The White House has also said if the aid is passed it will immediately acquire ground-to-air shoulder-fired rockets, possibly Stingers, for the contras to use against the Sandinistas' Soviet-made Mi24 helicopter gunships. The administration does not view the rockets as escalating the conflict.

"What about those gunships themselves? They are the escalation," said Deputy Assistant Secretary of State William G. Walker.