WASHINGTON — Interest rates on short-term Treasury bills jumped in Monday's auction, with the rate on three-month bills reaching its highest level in 10 years.

The Treasury Department auctioned $48 billion in three-month bills at a discount rate of 1.910 percent, up from 1.895 percent last week. Another $42 billion in six-month bills was auctioned at a discount rate of 2.070 percent, up from 2.030 percent last week.

The six-month rate was the highest since those bills averaged 2.050 percent on June 16, 2008, before the onset of the financial crisis. The three-month rate was the highest since May 21, when those bills averaged 2.08 percent.

The discount rates reflect that the bills sell for less than face value. For a $10,000 bill, the three-month price was $9,952.72 while a six-month bill sold for $9,895.35. That would equal an annualized rate of 1.946 percent for the three-month bills and 2.121 percent for the six-month bills.

Separately, the Federal Reserve said Monday that the average yield for one-year Treasury bills, a popular index for making changes in adjustable-rate mortgages, stood at 2.28 percent last Friday, up from 2.17 percent on Tuesday, May 29.