BEIJING—The British businessman whose death has emerged as a key element in China's biggest political scandal in two decades periodically consulted for a British strategic-intelligence firm founded by ex-spies, a spokesman said Monday.

Neil Heywood, who was found dead in a Chongqing hotel room in November, wasn't a full-time employee of the firm, Hakluyt & Co., and wasn't involved in projects in Chongqing, the spokesman said. The work was apparently one of several jobs Mr. Heywood held. The level of sensitivity of his projects...