Sixty-five private organizations called on the Carter administration yesterday to grant emergency food relief to Laos and Vietnam, where harvest setbacks and other problems have resulted in substantial food deficits.

The organizations include the National Council of Churches, the U.S. Catholic Conference, the League of Women Voters and a number of farm groups.

The State Department has told private citizens that it appears Vietnam is short as much as 1 million tons of rice. The United Nations Development Fund has estimated that Laos has a food deficit of 367,500 tons and could exhaust its food supplies by next March unless help is forthcoming.

The State Department says food aid and foreign assistance laws recently passed by Congress prohibit aid to Vietnam. However, Gareth Porter, spokesman for the private organizations that made the appeal yesterday, maintained that sections of the 1977 foreign aid law permit help to alleviate human suffering caused by natural and manmade disasters, regardless of national exclusions.

In a form letter replying to private citizens' letters about the food situation, the State Department has said that the "administration has no plans to provide food aid to Vietnam."

The letter concedes that the situation in Vietnam is "quite serious" and acknowledges that bad weather is partly to blame. But it also blames action by the new Communist government in the South. The letter cites "the dismantling of the traditional marketing system" for rice, "efforts to collectivize agriculture," and "general mismanagement."

Vietnam had planned to produce 9.274 million tons of paddy rice this year, but fell short. Typhoon Sarah hit four delta provinces July 21, causing a loss of 200,000 tons.