WASHINGTON( AP)—Interest rates on six-month Treasury bills remained at a record low, while rates on three-month bills dipped to the lowest level since December.

The Treasury Department auctioned $30 billion in six-month bills at a discount rate of 0.150 percent, unchanged from last week when they had declined from the previous record of 0.190 percent. Since late August, the bills have been at levels not seen during the last half-century that the government has been issuing them on a weekly basis.

The rate for three-month bills dropped to 0.070 percent, down from 0.075 percent last week and the lowest level since 0.050 percent on Dec. 29. The government sold $30 billion in three-month bills.

The discount rates reflect that the Treasury bills sell for less than face value. For a $10,000 bill, the three-month price was $9,998.23, while a six-month bill sold for $9,992.42. That would equal an annualized rate of 0.071 percent for the three-month bills, and 0.152 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, fell to 0.36 percent last week from 0.39 percent the previous week.