BEIJING, June 28 (Xinhua) -- China's central bank drained 100 billion yuan (about 15.1 billion U.S. dollars) from the financial system through open market operations Thursday, with the volume of maturing securities exceeding new injections.

The People's Bank of China (PBOC) pumped 80 billion yuan into the market through reverse repos, with 180 billion yuan of contracts maturing, leading to a net withdrawal of 100 billion yuan.

The PBOC said the move was to maintain liquidity at the end of the first half.

The overnight Shanghai Interbank Offered Rate (Shibor) dropped 15.60 basis points to 2.2890 percent Thursday.

The PBOC announced Sunday that it would cut the reserve requirement ratio (RRR) for some commercial banks by 50 basis points, expecting to release a total of 700 billion yuan into the banking system.

PBOC said the cut, the third this year following reductions in January and April, was "a targeted, precision regulation" to boost funding for small and micro firms as well as support the debt-to-equity swap program. The cut will take effect on July 5.

China will maintain a prudent and neutral monetary policy in 2018 as it balances growth and risk prevention.