WASHINGTON — Mortgage rates, which had been sliding, went up this week, disappointing news to would-be home buyers.

Freddie Mac, the mortgage company, reported Thursday that 30-year, fixed-rate mortgages averaged 6.11 percent. That was up from last week's rate of 5.96 percent, which was the lowest in more than two years. Until this week, rates on 30-year mortgages had been falling or holding steady each week since the middle of October.

The pickup in mortgage rates around the country comes as some prospective home buyers struggle with a credit crunch that has made it more difficult to secure financing for homes and other big-ticket purchases. The worsening credit crunch has aggravated the housing slump, which is weighing heavily on national economic activity.