Sales of existing homes rose 2.1 percent in August, continuing a three-month rebound, a real estate trade group said this week.

The National Association of Realtors, which released the sales figures, forecast a slowdown in the fourth quarter because of rising mortgage rates.

The group said house resales totaled a seasonally adjusted annual rate of 3.40 million units compared with July's revised 3.33 million rate. Sales rose 0.9 percent in June from the 1990 low of 3.30 million units in May.

"Despite rising {interest} rates, the resale market is stable and slightly better than July," said Norman D. Flynn, president of the group. "The strength we see largely is due to people who are buying homes in less populous areas and recreational areas."

However, the group's chief economist, John A. Tuccillo, said mortgage rates will rise during most of the fourth quarter, having a negative impact on existing-home sales.

Fixed-rate, 30-year mortgage rates rose from 9.84 percent to 10.24 percent in August, according to the Federal Home Loan Mortgage Corp. The rates averaged 10.16 percent at the end of last week.

The trade group also said the national median existing-home price was $97,000 in August, down 1.3 percent from July, but up 1.3 percent from a year earlier. The median means half of the homes cost more, half less.

Flynn said a decrease in the national median home price from July to August indicates sellers are bringing down prices in response to rising interest rates.

"This is a typical occurrence," he said.

Sales climbed 6.9 percent to an annual figure of 1.40 million in the South, where the median price was $86,900. Sales rose 2.2 percent to 950,000 units in the Midwest. The median price there was $75,000.

Home sales fell 1.8 percent in the sluggish Northeast to 550,000 units. The median price in the Northeast was $144,900.

Sales also dropped 3.8 percent to 530,000 units in the West, where the median price was $141,600.