YAMALES, HONDURAS -- As wounded ex-combatants and family members of the Nicaraguan contras still in Honduras begin to return home, they complain that they are being underfed by the United Nations, which assumed responsibility for their care here after a U.S. program expired in April.

Leaders of the approximately 5,000 Nicaraguans in Yamales, the contras' former headquarters, allege that since the U.S. Agency for International Development (AID) stopped feeding them, 40 children have died of malnutrition and related maladies, while the adults in the encampments frequently go hungry and lack basic medical supplies.

"We miss AID. When they were involved we had a lot of food," said Carlos Garcia Agurto, 29, a former fighter who was left in charge of the Nicaraguan family members in Honduras when the contras returned to Nicaragua in March and April for demobilization.

An official of the United Nations High Commission for Refugees, in charge of providing assistance to the Nicaraguans, acknowledged logistical difficulties in taking over the AID program but said the problems have been largely overcome.

Ulrich Von Blumenthal, the deputy representative of the U.N. High Commissioner in Honduras, said a small number of children have died while under U.N. care, but he said the deaths resulted from factors not related to the shift in management of the project.

Some officials involved say the United States had been providing too much food. In any case, the difficulties appear to stem from a change in the formula used to determine how much food the Nicaraguans receive.

Under AID, the fighters received 100 percent of their needs while dependents received supplemental assistance, amounting to 30 to 40 percent of their requirements, according to AID officials. The United Nations has provided everyone the same amount, so that many ex-combatants who were on full rations are receiving less than before, while some dependents are receiving more, von Blumenthal said.

On May 1, the contras' dependents and the ex-combatants came under the care of the International Support and Verification Commission, a joint U.N.-Organization of American States group created last summer to oversee contra demobilization and their reintegration into Nicaraguan society.

In Honduras, the commission's responsibilities were undertaken by the U.N. High Commissioner, while inside Nicaragua, the Organization of American States is caring for the contras and their family members.

The U.N. effort here differs from the program that cares for an estimated 20,000 Nicaraguans in Honduras under a formal refugee status.

Refugees in Honduras have begun to return to Nicaragua, and von Blumenthal said about 1,000 dependents were expected to return to Nicaragua weekly through the end of the year.

In the spring of 1988, following a cutoff of U.S. military aid to the rebels, an estimated 12,000 contras entered Honduras from Nicaragua. The contras and their dependents came under care of AID.

Relying on figures provided by the contras' leadership, the United States provided food for about 40,000 non-combatants. But a U.N. census of the dependent population as of May 1 counted only 25,000 Nicaraguans -- 5,000 in Yamales, the rest in other parts of Honduras -- who qualify for their care, von Blumenthal said.

Some international officials involved in both the U.S. and the U.N. programs feel the discrepancy in numbers indicates that AID was providing food for nonexistent Nicaraguans. "They were not in control of the program," said one official involved in the current project.

A U.S. official in Honduras said that while the AID program was constantly audited, an exact census was never taken. An AID official said the numbers were determined by registering the head of each family and figuring in an average of eight members per family.

"The system that was set up was believed to be adequate. We had every indication that it was effective," the U.S. official said.

Both von Blumenthal and the U.S. officials said that since the contra army returned to Nicaragua last spring, the dependent population has changed. Some individuals have returned to Nicaragua, while others might have chosen not to register for the U.N. program, which could account for the different figures.

In the past, the contras have been known to take advantage of U.S. foreign assistance programs to receive extra aid or to channel humanitarian aid to military programs.

In Yamales, where about 5,000 contra dependents are waiting to return to Nicaragua, the people complain that they are fed only rice and tortillas.