BEIJING, Jan 17 (Reuters) - China's central bank is preparing to raise the reserve requirement ratio for yuan deposits placed in yuan clearing banks from Jan. 25 in its latest bid to stem speculation in the currency, according to three sources who have seen the document outlining the change.

The People's Bank of China (PBOC), which had established the reserve requirement ratio (RRR) for offshore yuan participating banks in 2014, will return the rate to a normal level, the sources said, without specifying what that level would be. It had been set at zero.

(Reporting by the BEIJING bureau; Editing by Kim Coghill)