BEIJING, Oct 13 (Reuters) - Chinese banks extended 1.66 trillion yuan ($257.66 billion) in new yuan loans in September, up from August but falling short of analyst expectations. Analysts polled by Reuters had predicted new yuan loans would rise to 1.85 trillion yuan in September from 1.22 trillion yuan the previous month and against 1.9 trillion yuan a year earlier. Broad M2 money supply grew 8.3% from a year earlier, central bank data showed on Wednesday, above estimates of 8.1% forecast in the Reuters poll. M2 grew 8.2% in August from a year earlier. Outstanding yuan loans in September grew 11.9% from a year earlier compared with 12.1% growth in August. Analysts had expected 12.1% growth. ($1 = 6.4426 Chinese yuan renminbi) (Reporting by Judy Hua and Kevin Yao; Editing by Louise Heavens) Our Standards: The Thomson Reuters Trust Principles.