Interest rates on short-term Treasury securities rose in this week's auction to the highest level in two weeks.

The Treasury Department Monday sold $7.2 billion in three-month bills at an average discount rate of 8.69 percent, up from 8.65 percent last week. Another $7.2 billion was sold in six-month bills at an average discount rate of 8.76 percent, up from 8.66 percent last week.The rates were the highest since three-month bills sold for 8.73 percent on Feb. 27, and six-month bills averaged 8.77 percent on Feb. 27.

The new discount rates understate the actual return to investors - 9.01 percent for three-month bills with a $10,000 bill selling for $9,780.30 and and 9.29 percent for six-month bills selling for $9,557.10.

In a separate report, the Federal Reserve said the average yield for one-year Treasury bills, the most popular index for making changes in adjustable rate home mortgages, fell to 9.39 percent last week after averaging 9.40 percent the week before.