A surge in buyers and a drop in foreclosures have left a shortage of houses for sale in metro Phoenix, according to a newly released report on the state of the housing market.

The shrinking inventory has prompted bidding wars and pushed up home prices in many communities.

At the end of February, the supply of homes for sale was just under 24,000, down 42 percent from a year earlier, mostly because of a 52 percent drop in foreclosures during the past year, according to the latest monthly real-estate report from Arizona State University's W.P. Carey School of Business.

As banks take back fewer homes through foreclosure, fewer homes go to auction or back on the market.

Tuesday's report, which said that home prices could keep climbing if the inventory of homes for sale remains low, was the most optimistic from ASU since the beginning of the region's housing crash in 2007.

"Supply is tight, in a pretty extreme way, and it looks like it will stay that way for months," said Mike Orr, director of the Center for Real Estate Theory and Practice at ASU.

Orr said that as long as supply is tight and there are more buyers than sellers, Phoenix-area home prices will continue to climb.

Metro Phoenix's median home price has steadily been increasing since last August, when it fell to a 12-year low of $113,000. The region's median for February was $124,500, up 8 percent from a year earlier.

Climbing home prices could entice more homeowners who bought before the boom to try to sell their homes.

More sellers would increase supply, balancing the market and aiding many frustrated buyers who are currently being outbid on foreclosures and short-sale homes.

"Now, I have a ton of buyers and no properties to sell them," said Diane Brennan of Scottsdale-based Keller Williams Integrity First Realty.

"I warned buyers for months they should act quickly. Many didn't pull the trigger before because they were waiting for the bottom," she said.

There is a potential problem lurking in the recent trend: Some appraisals aren't keeping pace with the increases in home prices.

Orr said appraisers are still looking at prices from three months ago.

In some parts of metro Phoenix, though, home prices have climbed 5 percent or more since the beginning of the year.