BEIJING, Dec. 28 (Xinhua) -- China's central bank injected liquidity into the money market through reverse repos Friday to maintain liquidity.

The People's Bank of China (PBOC) conducted 150 billion yuan (21.86 billion U.S. dollars) of seven-day reverse repos at an interest rate of 2.55 percent and 100 billion yuan of 14-day reverse repos at 2.7 percent.

Previous reverse repos worth 30 billion yuan matured Friday, meaning that the net market injection came in at 220 billion yuan.

The PBOC said in a statement that Friday's operation is aimed at maintaining reasonable and sufficient liquidity in the banking system.

Through reverse repos, the central bank purchases securities from commercial banks through bidding with an agreement to sell them back in the future.