WASHINGTON DC, United States — HOME prices in major US cities rose in May for the second straight month, propped up by a flurry of spring buyers. But after adjusting for such seasonal factors, prices fell in a majority of markets.

The Standard & Poor’s/Case-Shiller home-price index released yesterday showed that prices rose in 16 of the 20 cities tracked.

Boston posted the biggest monthly increase, followed closely by Minneapolis and Washington. Prices in three metro areas hit the hardest by the housing crisis — Detroit, Las Vegas and Tampa (Florida) — fell to their lowest points since the recession began. Prices in Phoenix were unchanged.

The 20-city rose one per cent in May from April. The index measures prices compared with those in January 2000. It then provides a three-month average. The May data is the latest available.

Separately, the Commerce Department said fewer people bought new homes in June from May. Sales fell one per cent last month to a seasonally adjusted annual rate of 312,000. That’s less than half the 700,000 that economists say is typical in healthy markets.

Housing remains the weakest part of the economy. High unemployment, larger down payment requirements and tighter credit are preventing many buyers from entering the market. Many who can afford to buy are waiting because they are worried prices have yet to hit bottom.

Analysts say home prices have stabilised over the past six months. But uncertainty over unemployment and millions of foreclosures that have been delayed because of a government investigation could easily send prices downward in the coming months.

Robert Shiller, a Yale professor and co-founder of the home-price index, said too much of the economic picture remains up in the air to make any realistic projection about where home prices are headed.

“The aggregate economy is at a turning point and there is much uncertainty now,” he said.

David M Blitzer, chairman of S&P’s index committee, said the month-over-month increase in May was attributed to a “seasonal period of stronger demand for houses”. Such increases are expected, he said.

“Sustained increases in home prices over several months and better annual results need to be seen before we can confirm a real estate market recovery,” he said. Over the last 12 months, prices have fallen in 19 of the 20 cities tracked.

One bright spot: Even when adjusted for seasonal factors, month-over-month prices rose in some markets that had been pummeled by slumping sales. Those cities are Chicago, Denver, Miami, Minneapolis, and Seattle.

Still, prices in 11 markets fell when adjusted for the spring-buying season: Atlanta, Charlotte, Cleveland, Dallas, Detroit, Las Vegas, Los Angeles, Phoenix, Portland, San Diego, and Tampa (Florida).

Last year, a tax credit for first-time buyers helped boost prices. They rose nearly four per cent from April through July before falling more than seven per cent this winter to record lows. Prices in big metro areas sank in March to their lowest levels since 2002.

Americans are holding off from buying homes for a variety of reasons.