WASHINGTON — Interest rates on short-term Treasury bills rose in Monday’s auction with rates on six-month bills rising to the highest level since March 2011.

The Treasury Department auctioned $32 billion in three-month bills at a discount rate of 0.105 percent, up from 0.100 percent last week. Another $28 billion in six-month bills was auctioned at a discount rate of 0.150 percent, up from 0.145 percent last week.