Treasury bill yields rose for the third week in a row at the government's weekly auction yesterday, reaching the highest levels since last summer and fall, officials said.

The government sold $6.2 billion of three-month bills at an average discount of 9.09 percent, up from 8.98 percent last week, and $6.2 billion of six-month bills at an average discount of 9.14 percent, up from 9.02 percent last week.

The yields were the highest since the Aug. 9, 1982, level of 10.025 percent for three-month bills and the Oct. 4 level of 9.229 percent for six-month bills. Six-month bills have now risen for eight straight weeks, while three-month bills have risen in six of those weeks.

The investment yield for the latest Treasury bills, showing the return on investment, was 9.46 percent for the three-month bills and 9.74 percent for the six-month bills.

The three-month rate is the maximum yield of 91-day savings certificates available in denominations of $2,500 or more. Their new rate thus is 9.09 percent.

The highest rate that banks and savings and loan associations may pay on six-month money market certificates issued in denominations of $2,500 or more is the six-month bill rate plus a quarter point, or 9.39 percent, up from 9.27 percent last week.