Yields for 13-week Treasury bills rose while 26-week bill rates fell at the regular weekly auction.

The Treasury Department auctioned $7.213 billion worth of 13-week bills at an average discount of 8.51 percent, up from 8.49 percent at last week's auction.The government also sold $7.209 billion worth of 26-week bills at an average discount of 8.50 percent, down from 8.54 percent last week.

This was the highest rate for the 13-week bills since Feb. 6, when the bills had a rate of 8.57 percent. It was the lowest rate on 26-week bills since Jan. 30, when the rate was 8.39 percent.

The discount rate understates the actual yield to investors. The investment, or coupon-equivalent, rate was 8.82 percent on the 13-week bills at an average price of $9,784.90 per $10,000 face value. The investment rate on the 26-week bill was 9.00 percent at an average price of $9,570.30 per $10,000 face value.