BEIJING - During its last open market operation for March on Thursday, the People's Bank of China (PBOC) took 297 billion yuan ($45.3 billion) of liquidity out from China's banking system, the first monthly net tightening since September 2010.

PBOC Thursday auctioned 26 billion yuan ($3.97 billion) of three-month bills and sold another 60 billion yuan of repurchase agreements.

The central bank had already frozen another 360 billion yuan of money through hiking banks' reserve requirement ratio by 50 basis points on March 25, thus making China's major banks keep a record high 20 percent of their deposits in reserve.

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Analysts said PBOC's open market operations in March showed the central bank will maintain a relatively tight monetary policy in the second quarter.

"We can't rule out the possibility of another reserve requirement ratio hike in April as the market expects the consumer price index to climb to a new record high in March, pressuring PBOC to tackle inflationary expectations," said Wang Shen, an analyst with Shenyin and Wanguo Securities Co Ltd.

China still faces liquidity problems as bills and repurchase agreements worth more than 900 billion yuan will mature and be released in the open market in April.