WASHINGTON — Rates on 30-year mortgages rose for a fourth consecutive week, climbing to the highest level since late March, as financial markets continued to worry about inflation.

Mortgage giant Freddie Mac reported yesterday the nationwide average for 30-year, fixed-rate mortgages rose this week to 5.98 percent, up from 5.91 percent last week. It was the highest level since rates rose the week of March 31 to 6.04 percent, which so far has been the highest nationwide average for the 30-year mortgage so far this year.

"Mortgage rates have been rising for the last four weeks on inflation jitters caused in part by extended higher energy prices," said Frank Nothaft, chief economist for Freddie Mac.

Rates on 15-year, fixed-rate mortgages, a popular choice for refinancing a home mortgage, averaged 5.54 percent this week, up from 5.48 percent last week.

One-year adjustable rate mortgages rose to 4.77 percent, the highest level in more than three years, and up from 4.68 percent last week.

Rates on five-year hybrid adjustable rate mortgages averaged 5.48 percent this week, up from 5.31 percent last week.

The nationwide averages for mortgage rates do not include add-on fees known as points. The 30-year and 15-year mortgages carried a nationwide average fee of 0.5 point while the five-year and one-year ARM carried a fee of 0.6 point.

A year ago, 30-year mortgages averaged 5.82 percent, 15-year mortgages were at 5.24 percent and one-year ARMs averaged 4.08 percent. Freddie Mac does not have historical data on the five-year ARM which it began tracking this year.