John S. Benz, 70, a retired official of the Agency for International Development whose overseas assignments included London, Pakistan, Laos, Nepal and Yemen, died Friday at the Wisconsin Avenue Nursing Home. He had cancer.

Mr. Benz, who was born in Milwaukee, earned a bachelor's degree in education from Wisconsin State College and a master's degree in economics from the University of Wisconsin. He began his government career with the Census Bureau in 1938. He worked in San Francisco and Philadelphia and was transferred to Washington about 1941.

During World War II, he was a captain in the Army and served in Britain. He returned to the Census Bureau after the war.

In 1949, he joined the Marshall Plan, which was to revive the post-war economy of Western Europe, and spent the next six years in London.

He later served in Pakistan and Laos. He also had a number of assignments in Washington. After the government's foreign aid programs were reorganized under AID in 1961, Mr. Benz served as the agency's program director in Yemen and Nepal.

At the time of his retirement in 1970, he was assigned to the auditor general's office in Washington. He was a recipient of AID's Distinguished Honor Award.

Mr. Benz, who lived in Washington, was a consultant to private businesses and the government following his retirement.

Survivors include a sister, Esther Benz of Detroit.

The family suggests that expressions of sympathy be in the form of contributions to the Vincent T. Lombardi Cancer Research Center, Georgetown University Hospital, Washington, 20007.