WASHINGTON — Rates on 30-year mortgages dipped slightly this week as evidence grew of more troubles in the slumping housing market.

Freddie Mac, the mortgage company, reported yesterday that 30-year fixed-rate mortgages averaged 6.69 percent this week, down from 6.73 percent last week. The high point for this year was a rate of 6.74 percent hit in mid-June.

Various reports this week showed that the slump in housing, which had enjoyed boom conditions for five years, was continuing. Sales of both new and existing homes fell sharply in June, and one of the nation's biggest mortgage lenders reported a sharp drop in profits for the second quarter because of rising loan defaults.

"Mortgage rates eased this week on market concerns that a further weakening of housing demand this spring will delay any recovery in this sector," said Frank Nothaft, chief economist at Freddie Mac.

According to the Freddie Mac survey, rates on 15-year fixed-rate mortgages edged down slightly to 6.37 percent this week, compared with 6.38 percent last week.

Rates on five-year adjustable-rate mortgages averaged 6.30 percent, down from 6.35 percent last week. Rates on one-year adjustable-rate mortgages edged down to 5.69 percent, compared with 5.72 percent last week.

The mortgage rates do not include add-on fees known as points. The 30-year, 15-year and five-year mortgages all carried a nationwide average fee of 0.4 point. The one-year adjustable-rate mortgage carried an average fee of 0.5 point.

A year ago, rates on 30-year mortgages stood at 6.72 percent, 15-year mortgages were at 6.34 percent, five-year adjustable-rate mortgages averaged 6.35 percent and one-year ARMs were at 5.78 percent.