WASHINGTON (AP) — Average U.S. rates on fixed mortgages were little changed this week, staying near their lowest levels in three months.

Mortgage buyer Freddie Mac said Thursday that the average rate on the 30-year loan edged up to 4.23 percent from 4.22 percent last week. The average on the 15-year fixed loan rose to 3.31 percent from 3.29 percent.

Both are the lowest averages since July.

Mortgage rates began falling last month after the Federal Reserve held off slowing its $85-billion-a-month in bond purchases. The bond buys are intended to keep longer-term interest rates low, including mortgage rates.

Longer-term rates have also stayed low because of the partial government shutdown and a lack of government economic data.

The shutdown that began this month has spurred investors to sell stocks and buy Treasury bonds. Mortgage rates tend to follow the yield on the 10-year Treasury note. The 10-year note traded at 2.67 percent Wednesday, up from 2.63 percent last week but down from 2.71 percent on Sept. 23.

The shutdown could also slow the housing recovery, if it last for more than a few weeks.

Some prospective borrowers are finding it harder to close on their mortgages. And some lenders are having a hard time getting confirmation of applicants' income tax returns and Social Security data because of government agency closures, delaying some mortgage closings.

Furloughs at the Federal Housing Administration are slowing the agency's processing of loan guarantees for some low- to moderate-income borrowers and first-time homebuyers. About 30 percent of U.S. home mortgages are insured by the FHA.

To calculate average mortgage rates, Freddie Mac surveys lenders across the country on Monday through Wednesday each week. The average doesn't include extra fees, known as points, which most borrowers must pay to get the lowest rates. One point equals 1 percent of the loan amount.

The average fee for a 30-year mortgage was steady at 0.7 point. The fee for a 15-year loan also was unchanged at 0.7 point.

The average rate on a one-year adjustable-rate mortgage ticked up to 2.64 percent from 2.63 percent and the fee held at 0.4 point.

The average rate on a five-year adjustable mortgage increased to 3.05 percent from 3.03 percent. The fee fell to 0.4 point from 0.6 point.