That's slightly higher than last Tuesday's sale of CNY20 billion, which saw yields rise to 1.8434% from the previous result of 1.7650%, the first rise since August 11.
The central bank last Tuesday also raised banks' deposit reserve requirement by 50 basis points, its first hike since June 2008.
The PBOC sold CNY50 billion in three-month paper last Thursday but the yield unexpectedly came in at 1.3684%, flat from the previous week's result.
The central bank mopped up a net CNY102 billion from the banking system last week after draining CNY137 billion in the previous week.
Traders said interbank liquidity is a bit tighter this week as the reserve hike took effect on Monday, taking away some CNY300 billion while eight initial public offerings also start taking subscriptions this week.
