WASHINGTON (AP) _ Existing home sales declined 2.2 percent in January as rising mortgage interest rates combined with the usual winter lull to brake sales to their slowest pace since last summer, a real estate trade group said Wednesday.

The National Association of Realtors said resales of single-family homes totaled a seasonally adjusted 3.48 million units in January, compared to 3.56 million one month earlier. It was the slowest pace since last August's 3.44 million rate.

John A. Tuccillo, the Realtors' chief economist, said he did not see a big increase in existing home sales in the near future, but added that ''as rates taper off in the spring, we expect sales to pick up.''

Surveys by the Federal Home Loan Mortgage Corp. show that fixed-rate, 30- year mortgages rose from 9.83 percent to 10.05 percent during January.

''The rate rise in January made a dent, in high-end and less-expensive markets,'' said Realtors' President Norman D. Flynn, who also noted that the start of a new year is a slow home-sales period.

The housing market has been hurt by the Federal Reserve's high interest policies designed to stem inflation by slowing the economy. Existing home sales dropped to a 3.25 million rate last May when mortgage rates were still near their peak.

The Commerce Department is scheduled to release on Friday its report on new home sales in January.

The Realtors' survey found the median price of an existing home to be $96,200, up 4 percent from December and 7.1 percent from January 1989. The median means half of the homes cost more, half less.

The only increase in resales occurred in the South where 1.40 million units were sold on an annual rate, up 0.7 percent from December. The median price there was $86,300.

Sales in the West, where the median price was $144,000, suffered the biggest decline, down 11.5 percent to 540,000 million units.

The Northeast posted a 3.4 percent drop to 560,000 units. The median price there was $147,100.

The Midwest experienced a decline of 2 percent to 960,000 units. It had a median price of $74,600.