The 6-month yield rose 05 basis points to 10.15 percent and the 12-month yield rose 05 basis points to 11.19 percent.
The debt office said 16 billion bills matured and 12.44 billion rupees in bids were accepted from the market. It sold 2.9 billion rupees in three month bills, 1.0 billion rupees in 6-month bills and 8.4 billion rupees in 12-month bills.
Analysts say it is important to allow Treasury bill yields to go up and down depending on credit demand to keep inflation down and the exchange rate stable.
Sri Lanka's central bank buys foreign exchange to prevent the rupee going up, creating liquidity, and when it also buys Treasury bills injecting rupee reserves to the banking system it generate pressure on the rupee peg and high inflation.