China's central bank drained 50 billion yuan (7.5 billion U.S. dollars) from the financial system through open market operations Monday as the volume of maturing securities exceeded new injections.

The People's Bank of China (PBOC) pumped 180 billion yuan into the market through reverse repos, a process by which the central bank purchases securities from commercial banks through bidding with an agreement to sell them back in the future.

The operations included 100 billion yuan of seven-day reverse repos priced to yield 2.45 percent and 80 billion yuan of 14-day reverse repos with a yield of 2.6 percent.

The injection was offset by 230 billion yuan in maturing reverse repos on Monday, leading to a net withdrawal of 50 billion yuan.

The central bank made a net cash injection of 110 billion yuan last week via open market operations after withdrawal for two consecutive weeks.

In Monday's interbank market, the overnight Shanghai Interbank Offered Rate (Shibor), which measures the cost at which banks lend to one another, rose slightly to 2.8482 percent.

The PBOC's open market operations are closely watched by the market, as they are major tools for the central bank to manage liquidity.

The central bank has increasingly relied on open market operations for liquidity management, rather than cuts in interest rates or reserve requirement ratios.

China set the tone of its monetary policy in 2017 as prudent and neutral, keeping an appropriate liquidity level but avoiding excessive liquidity injections.