Sept 25 (Reuters) - Hong Kong stocks posted their biggest one-day loss in six weeks on Monday, with a slump in property shares hitting already fragile sentiment after the Federal Reserve's hawkish stance and Standard & Poor's downgrade of China's credit rating last week.

The Hang Seng index dropped 1.4 percent, to 27,500.34 points, while the Hong Kong China Enterprises Index lost 1.8 percent, to 10,912.46.

An index tracking mainland developers tumbled more than 8 percent, after some cities in China imposed new housing controls to hose down an overheated market.

Investor sentiment was also undermined by simmering concerns that China's beefed-up environmental protection could reduce demand, and consequently economic growth. Hong Kong has close economic and financial links with the mainland.

UBS strategist Gao Ting said that some top-down investors now anticipate a slowdown in China's GDP growth, and worry about the sustainability of the global economic recovery.

Stocks fell across the board.

An index tracking resource shares slumped over 3 percent. (Reporting by Samuel Shen and John Ruwitch; Editing by Jacqueline Wong)