The ratio of bids to the amount of the latest three-month bill issue offered was 3.40, lower than 3.70 at the prior three-month T-bill sale last week.
Treasury bill rates and other short-term US borrowing costs jumped last week as the minutes on the Federal Reserve's April policy meeting suggested policymakers are ready to raise US interest rates in June if the economy improves further.
Meanwhile, the Treasury sold $26 billion in six-month T-bills at an interest rate of 0.480 percent, up from 0.370 percent last week and the highest level since the auction on March 14.
The bid-to-cover on the latest six-month bill issue was 3.65, down from the prior week's 4.00 and the lowest in eight weeks.