For the first time in more than a decade, home prices could start to fall around the country in coming months, the National Association of Realtors said yesterday after a report showed that sales of existing homes fell in June and the number of homes for sale soared to their highest point since 1997.

Condo prices already are being hit: They fell 2.1 percent from June last year to a median $226,900. Prices of single-family homes edged up 1.1 percent in June to $231,500. With a 6.8-month supply of single-family homes on the market and an eight-month supply of condos, sellers are under more pressure to cut prices, and buyers can be choosy.

David Lereah, NAR's chief economist, said he expects prices to start "deteriorating," though he still projects home prices will be up 5.3 percent for the year.

The new figures provide deeper evidence that the nation's housing market is undergoing a jarring transition from a seller's to a buyer's market. The five-year boom, which peaked in August, was driven partly by investors, who snapped up 28 percent of homes sold last year. Many of them now want to sell. But rising interest rates and lofty home prices have squeezed out many buyers.

"Prices got too high in some local markets," Lereah said. "So you're seeing two things occur: Investors are leaving quickly, and regular home buyers are staying on the sidelines."

On O'ahu, homes are sitting on the market longer this year, and fewer sales have helped double inventory levels of last year. Economists forecast that 2006 prices will rise around 10 percent, which if accurate would be the smallest gain since 2001 and well off last year's growth rate of nearly 30 percent.

In June, the median O'ahu single-family home price was up 7.7 percent to $639,000 over last year, and the median condo price was up 17.4 percent to $310,000.

The last time national single-family home prices fell was in April 1995, when they slipped 0.1 percent. The NAR said June existing-home sales slipped 1.3 percent from May, to a seasonally adjusted annual rate of 6.62 million, and were down 8.9 percent from June 2005. Tomorrow, the Commerce Department will report new home sales for June, and economists such as Phillip Neuhart of Wachovia expect those figures, too, to show continuing weakness.

"The numbers are not fully counting cancellations, which builders are reporting at a very high level," Neuhart noted.

Many developers received approval for their projects when demand was sizzling. Now, some have to offer vacations, pools and car leases to entice buyers.

For existing-home sales, the weakest region was the West, where sales plunged 17.1 percent from June 2005. Sales fell 9.8 percent in the Northeast, 6.2 percent in the Midwest and 5.5 percent in the South.

"Markets which have been the hottest are quite likely to see home price declines," says John Ryding, an economist at Bear Stearns. "In those markets, you could see declines for the year."

The California Association of Realtors said yesterday that home sales skidded 26 percent from June last year and are off 20 percent for the year. Though the median-priced home statewide hit a record $575,800, prices fell in five areas.

"Affordability has probably hit a record low," said Robert Kleinhenz, CAR deputy chief economist.

Ron Peltier, CEO of HomeServices of America, added, "There is a delayed reaction on the part of sellers to accept the new reality."

Staff writer Andrew Gomes contributed to this report.