Virginia Gov. Charles S. Robb has named an executive of a major chemical firm that has clashed with state pollution officials to one of his administration's top environmental posts, and agreed to let the official continue to receive benefits from his current employer.

The unusual action will allow Richard L. Cook, manager of safety, health and environmental affairs for the E.I. du Pont de Nemours Inc. textile fibers plant in suburban Richmond, to become deputy secretary of commerce and resources. The $65,000-a-year position was created by the state legislature last year to focus more state attention on environmental problems.

Cook, 55, who will return to Du Pont at the end of a one-year leave, will continue to be eligible for life insurance, health and dental benefits from Du Pont and will not lose his pension seniority at the company while serving in the state government. In addition, he has received permission to accept a one-time bonus from Du Pont for work he did for the chemical firm.

His appointment was praised today by several environmental leaders in the state, but his continuing ties to Du Pont were questioned by some national environmental leaders.

"If he hasn't severed all ties to his company, I think there is definitely a problem," said Elizabeth L. Raisbeck, director of the Washington office of the Friends of the Earth. "Maybe in the technical sense he is not in conflict of interest but there is a lot more than technical questions in these things. There is the appearance of conflict."

"Certainly if the agreement was replicated in Washington, we'd raise the roof. And it would be, in my view, a conflict," said Blake Early, Washington representative of the Sierra Club. "But things work differently down there in Richmond. The whole approach down there is much less antagonistic, mainly because the environmental movement doesn't have much juice. They don't have political clout."

The environmentalists said that many environmental issues in Virginia involve Du Pont, whose six manufacturing facilities in the state produce hazardous wastes, emit air pollutants and discharge into the streams and rivers. In March, the firm agreed to pay Virginia nearly $2 million to settle claims of mercury contamination in state rivers.

Local environmentalists, however, had high praise for the appointment and said they were not troubled about the ties that Cook will maintain with Du Pont. "Dick Cook is an excellent choice," said David S. Bailey, director of the Virginia office of the Environmental Defense Fund. "We have always found him to be reliable, dependable and of the highest integrity."

Cook, who has worked for Du Pont for 25 years, cleared his financial arrangement with the state attorney general's office. The arrangement would not violate Virginia's conflict-of-interest law, because Cook will receive less than $10,000 from Du Pont and because his stock holdings in the firm are below the 3 percent limit set by state law, according to Attorney General Gerald L. Baliles.

Baliles also said that Cook should disqualify himself on issues "where Du Pont might be involved and have an interest." Cook has said he will not get involved in any cases directly involving Du Pont. "Du Pont would be disappointed in me if I did not disqualify myself ," Cook said today. "It's the way they operate."

Secretary of Commerce and Resources Betty J. Diener, who will be Cook's immediate boss, said his style fits the Robb administration's goal of balancing environmental concerns with economic goals.

Asked about the conflict issue, Diener replied, "You have to understand, he's a unique individual. . . in terms of his technical expertise. Both the governor and I were aware of this specific issue, and we talked to others . . . we felt it was more than justified, even though we knew the question would come up, as it has.