BEIJING, Oct 21 (Reuters) - China will continue to separate the operation of banking, securities and insurance businesses to maintain a stable financial system, its Central Bank Governor Yi Gang said on Thursday. In remarks at the Financial Street Forum in Beijing, he said that overly complicated financial business and product design would accelerate risks spreading to other sectors. (Reporting by Kevin Yao and Zhang Yan; Writing by Meg Shen; Editing by Edmund Blair)