The Reagan administration, contending that many Contra rebels inside Nicaragua are desperately short of food, will begin sending them cash at the rate of about $1 a day per rebel for food purchases, it was announced Friday. State Department spokeswoman Phyllis Oakley brushed aside complaints from House Speaker Jim Wright, D-Texas, that the rebels might use the money illegally to buy weapons. ``They already have weapons. What they need at this moment desperately is food, and we're confident that they will naturally use these small funds to provide for their basic survival,'' she said. An agreement signed between the Contras and Nicaragua's leftist Sandinista government on March 23 permits humanitarian aid for the rebels, but no shipments have been made thus far because of a dispute over how the assistance should be delivered, among other reasons. Meanwhile, many Contras inside Nicaragua were said to be suffering from an inadequate diet. As an interim measure, the administration about three weeks ago began arranging deliveries by truck and air drop of food to rebel camps in Honduras near the Nicaraguan border. Hundreds, perhaps thousands, of Contras have fled Nicaragua for Honduras in search of food in recent weeks. Officials from the Agency for International Development, in a preliminary discussion with reporters of the plan announced Friday, had said Monday that most of the aid will be in the form of Nicaraguan currency delivered by Contra couriers based in Honduras. Some food also will be delivered, but the emphasis will be on cash transfers because of limits on the amount of food that can be carried. AID was designated to manage the $48 million humanitarian aid program approved by Congress in late March, a week after the Contras and the Sandinistas reached a truce agreement that allows for such aid to the rebels. The secretary general of the Organization of American States, Joao Baena Soares, has criticized both deliveries of food to Contra camps in Honduras and the cash-for-food plan. Baena Soares, a member of a verification commission assigned to ensure compliance with the Contra-Sandinista agreement, has said that neither plan falls within the limits of what the two sides have approved. But an administration official said Wednesday that the other member of the commission, Nicaraguan Cardinal Miguel Obando y Bravo, has raised no objections to the cash-for-food plan. The administration has accused the Sandinista government of using delaying tactics during negotiations in a bid to starve the Contras into submission. But Nicaraguan Vice President Sergio Ramirez said Thursday his government is willing to allow immediate delivery of humanitarian supplies to rebels in Nicaragua. He denied that the government is trying to starve the Contras. ``We are in full disposition to accept that the Contra forces could receive humanitarian aid inside Nicaragua tomorrow, if possible,'' Ramirez told reporters after a 1{-hour meeting with Wright and other Democratic congressional leaders. Ramirez did not discuss his views on the cash-for-food plan. Wright has described the plan as a ``last resort'' because there are no guarantees the money won't be used to buy weapons. He also expressed concern that the cash might be used to buy weapons in violation of both the Contra-Sandinista agreement and the terms of the $48 million aid package. The package provides for food, clothing, shelter and medical supplies as well as treatment for children who are war victims. Money also was set aside to finance the work of the verification commission.