NEW YORK (CNN/Money) - Many homeowners who tried to refinance their mortgages at lower interest rates this summer are seeing the volume of applications choking the process, a report said Tuesday.

The rates borrowers have counted on to protect them against rising expenses are expiring before their loans get approved, according to the Washington Post. The slower-than-expected financing system resulted in climbing numbers of complaints to regulators from homeowners, the paper said.

"We've received many, many calls regarding complaints about interest rates lock-ins," E. Joseph Face Jr., commissioner of Virginia's Bureau of Financial Institutions, told the Post. "Our telephones have not stopped ringing."

In Maryland, the commissioner of financial regulation has received about 1,000 mortgage-related complaints so far this year, up from 863 in all of 2002. In the District, where the complaint tracking system is relatively new, regulators said they hadn't seen a major change, the paper said.

Mortgage rates fell to their lowest levels in more than 40 years earlier this year, and many borrowers rushed to refinance their mortgages.

But rates have since bounced off their lows, and problems occurred as many of the 60-day locks from the low point of the interest-rate cycle are now expiring.

Typically, a rate lock -- usually for 15 to 60 days -- is a security blanket for applicants, but according to those in the mortgage industry, the unprecedented volume of loan applications has slowed the system to a crawl. Sometimes that means the lock expires before the loan is ready to close.

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Average long-term fixed rates resumed an upward trend in the latest week, but rising mortgage rates failed to dampen the sizzling housing market, Freddie Mac said last week.

Thirty-year rates averaged 6.28 percent this week, compared with 6.24 percent the previous week, while 15-year mortgages inched upward to an average 5.60 percent from 5.58 percent last week, it said. Last week's averages for 30- and 15-year mortgages reflected the first declines in two months.

A year ago, 30-year mortgages averaged 6.27 percent, 15-year mortgages 5.71 percent.