WASHINGTON — Rates on 30-year mortgages, which had been falling for five weeks, jumped sharply this week, reflecting the turbulence in global credit markets.

Freddie Mac reported yesterday that in its nationwide survey the average for 30-year fixed-rate mortgages rose to 6.09 percent this week, up from 5.78 percent last week (the lowest since February).

The increase was blamed on turbulent financial markets, which have been hit by the biggest upheavals since the Great Depression.

The big declines in mortgage rates before this week were attributed in part to the government's announcement on Sept. 7 that it was taking over Fannie Mae and Freddie Mac following those companies' huge losses from soaring mortgage defaults amid the deep slump in housing.

Other mortgage rates in the Freddie Mac survey also rose this week.

Rates on 15-year fixed-rate mortgages, a popular choice for refinancing, rose to 5.77 percent, up from 5.35 percent last week.

Rates on five-year adjustable-rate mortgages averaged 6.02 percent this week, up from 5.67 percent. One-year adjustable-rate mortgages rose to 5.16 percent, from 5.03 percent last week.