WASHINGTON – Surging U.S. housing prices and a shortfall of available properties are putting a dent in home sales.

The National Association of Realtors said sales of existing homes slipped 1.8 percent in June to a seasonally adjusted annual rate of 5.52 million. Sales levels have been nearly flat for the past year, a sign that the housing market may be stalling amid the pressures of fewer listings and higher prices.

The number of sales listings has been falling on an annual basis for the past 25 months. There were 1.96 million homes for sale in June, a 7.1 decline from a year ago.

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"Sales have now made no progress over the past year, even as robust housing demand means those homes that are on the market are selling at a record pace," said Matthew Pointon, property economist, with Capital Economics, in a report.

He doesn't expect the shortage in homes for sale to abate this year.

The inventory of available homes has fallen roughly 9 percent over the last year, the biggest drop since 2013. Around the U.S., the hardest markets in which to find a home are Columbus, Ohio, Minneapolis and San Jose, California, according to Zillow.

Of the 35 largest metro areas around the country, Seattle, Dallas and Tampa have seen the greatest increase in value over the last year -- each has posted more than double-digit percentage gains.

The median sales price for existing homes has climbed 6.5 percent over the past year to $263,800, up from $248,000 a year ago.

Some experts think June dip in home sales is temporary, noting that the overall trend is up. Sales of existing properties last month were up 0.7 percent over the year-ago period.

"Through the volatility, the trend looks just modestly positive," said Jim O'Sullivan, chief U.S. economist with High Frequency Economics, in a note.