WASHINGTON — Rates on 30-year mortgages edged down this week, the first decline after six straight increases, according to a nationwide survey.

Mortgage giant Freddie Mac reported yesterday that rates on 30-year fixed-rate mortgages averaged 6.58 percent, down from 6.59 percent last week, which had been the highest level in nearly four years.

The Federal Reserve raised rates, as expected, for a 16th consecutive time at this week's meeting. But policy-makers left their options open for a possible pause in the two-year string of rate hikes this summer if the economy shows signs of slowing.

Frank Nothaft, chief economist at Freddie Mac, cautioned that mortgage rates could rise again next week if reports on consumer and wholesale prices re-ignite concerns about inflation.

Rates on 15-year, fixed-rate mortgages, a popular choice for refinancing a home mortgage, also fell this week, dropping to 6.17 percent, from 6.22 percent last week.

One-year adjustable rate mortgages dipped to 5.62 percent this week, down from 5.67percent last week.

Rates on five-year, hybrid adjustable-rate mortgages averaged 6.22 percent this week, up slightly from 6.21 percent last week.

The mortgage rates do not include add-on fees known as points. The one-year ARM carried a nationwide average fee of 0.7 point while the other three mortgage categories had an average fee of 0.5 point.

A year ago, 30-year mortgages averaged 5.77 percent, 15-year mortgages stood at 5.33 percent, one-year ARMs were at 4.23 percent and five-year ARMs averaged 5.21 percent.

Higher mortgage rates are slowing home sales this year after five consecutive years in which sales of both new and existing homes set records.