The United Nations says Mostafa Tolba, an Egyptian scientist who played a key role in the foundation of the U.N. environmental agency and was its executive director for 17 years, has died at age 93.

Achim Steiner, the current executive director of the U.N. Environmental Program, said Tolba died Monday in a clinic in Geneva.

In 1972, Tolba led Egypt's delegation to the Stockholm Conference on the Human Environment. It was there that his calls for "development without destruction" helped spur the establishment of the agency he would go on to lead. He was appointed director of the agency in 1976.

As director, Tolba fostered UNEP's most widely acclaimed success, the Montreal Protocol, a historic 1988 agreement to protect the ozone layer. It stands as a precedent for preventive rather than corrective international environmental action.