Virginia Gov. John N. Dalton, who for three years has complained about welfare costs, took the unprecedented step this week of withdrawing the state from a federal program that provided nearly $1 million a year for hundreds of mentally disabled Virginians.

Dalton laid his action -- the first time any state has withdrawn from the eight-year-old program -- to "exorbitant" and "burdensome regulations by overzealous federal administrators."

State officials said that while the governor has vetoed specific requests for federal grants, his action marked the first time in memory that the state has removed itself completely from a federal program.

Spokesman for groups representing the handicapped, who noted that Virginia was required to put up only 5 percent of the funds for the program, denounced Dalton's move today as potentially cruel and harmful. Some state legislators, especially those from Northern Virginia, where the program funded a number of projects, predicted a fight over the action.

"We'll do our best to fight it next month [when the legislature meets]," said Del. Mary Marshall (D-Arlington), a member of the House welfare committee. "I don't think the real issue is money so much as the fact that he [Dalton] is basically hostile to anyone who isn't fat and rich."

"I hope I'm wrong but it's possible that this will be the biggest step backward we've ever taken," said Claudia Bowen, executive director of the Virginia United Cerebral Palsy Association.

"He's basically giving money away that should come to the state and he's picking on a group of people who are the least able to fight back," said Chan Kendrick, state director of the American Civil Liberties Union.

The action was the latest in a series of cutbacks announced by the conservative Republican governor, who has cited Ronald Reagan's victory last month as proof that voters "want government out of their pocketbooks." In recent weeks the Dalton administration has devised a plan to chop nearly $30 million from the state Medicaid program by reducing hospital benefits to about 56,000 patients and cutting 750 nursing home patients off the program. Dalton also recently vetoed a $93,000 federal grant to the Virginia Food Law Project, a group promoting food stamps and nutritional programs for the poor.

"So many of our people have been led to believe that a job is owed to them by government, that a home . . . medical attention . . . food stamps . . . and assorted services are owed to them by government to relieve them of what Americans used to think were their own responsibilities," said Dalton in a speech last month in which he predicted further cuts in state welfare programs.

The federal Developmental Disabilities Program that Dalton eliminated awarded grants for programs such as group homes for mentally retarded adults and specialized training and foster care for disabled children. State officials and advocates for the handicapped estimated that more than 400 persons could be directly affected by the cutback.

"These aren't handouts," said Bowen. "What these programs do is provide money to make disabled people independent so that they become taxpayers rather than tax dependents."

In withdrawing from the program, Dalton contended federal law requires states to develop a computerized system to evaluate the plan's success that could cost Virginia $5 million in its first year. He also objected to a proposed regulation requiring the state to ensure employment for any worker who loses his job because of patient reductions at mental health institutions as a result of the program.

Lewis Zieske, executive director of the Virginia Association of Retarded Citizens, called the $5 million estimate "ludicrous." Zieske said it was his understanding that state officials had planned to use a computerized system already required under other federal programs to for the stipulated evaluation at a cost that would be "minimal to zero."

As for the employe regulation, Zieske noted it has not be approved and said the state has made no effort to change it.

A spokesman for the program, operated by the Department of Health and Human Services, said federal officials would try to negotiate with the state on Dalton's objections. The spokesman, who asked not to be identified, said other states had submitted estimates as low as $33,000 for the cost of the evaluation system that Virginia claimed would cost $5 million.

Dalton said the state "is concerned about its developmentally disabled citizens and will provide for them through established programs such as mental retardation, rehabilitative services, education and social service programs." But staff members of the state Developmental Disabilities Planning Council, which helped oversee the federal funding, said they had no idea at present where the money would come from to cover the gap left by the program's demise.

The federal government provided $943,680 for the program this year, while Virginia contributed $43,500.

"Even with the federal money, Virginia's record in this whole field of helping the handicapped has been very poor," said the ACLU's Kendrick. "Now there's a good chance it will get worse."