Fairfax County may have the largest force of building inspectors in Virginia, but the inspectors cannot halt work at construction sites suspected of violating state and federal occupational safety rules, Virginia Attorney General J. Marshall Coleman has warned the county.

He added, however, that local building officials could issue so-called "stop work" orders on any structure if the construction was considered unsafe and still did not involve a U.S. Occupational Safety and Health Administration standard.

In an opinion sought by Fairfax County Attorney Frederick Lee Ruck, Coleman said that only Virginia's commissioner of labor and industry has the power to obtain a court order to stop work because of OSHA violations.

Ruck has suggested that Fairfax County-which alone has many more building inspectors than the state - could assume an enforcement role.

The state attorney general suggested the state might be persuaded to amend its current OSHA plan to permit local enforcement. Such an action would be necessary because a state safety plan approved by the Labor Department excludes localities from OSHA enforcement, Coleman said.

The 1979 Virginia General Assembly passed a revised OSHA plan after the Labor Department found inadequacies in enforcement provisions in the old one. The new plan was opposed by the AFL-CIO, which said the safety and health of Virginia construction workers would be better served if the federal government took over all OSHA enforcement in the state.

Fairfax County has offered repeatedly to put its building inspectors at the disposal of the state.