SHANGHAI/BEIJING, Jan 24 (Reuters) - China's securities regulators have asked some hedge fund managers to restrict short selling in the country's stock index futures market, two sources said, as authorities seek to stabilise sinking stocks.

A hedge fund manager said he received calls from China's financial futures exchange, cautioning against reckless short selling, especially "naked" short selling conducted not for hedging purposes.

Another hedge fund source said the exchange had informally asked his firm recently not to short sell for speculative purposes. The sources spoke on condition of anonymity.

The China Financial Futures Exchange did not reply to a Reuters request for comment. Nor did the China Securities Regulatory Commission (CSRC), which oversees the exchange. (Reporting by Shanghai and Beijing newsrooms; Editing by Kim Coghill)