Contracts to buy previously-owned U.S. homes unexpectedly fell in June, casting a cloud over the housing market recovery.

The National Association of Realtors (NAR) said on Monday its Pending Home Sales Index, based on contracts signed last month, fell 1.1 percent to 102.7.

The decline, which confounded economists' expectations for a 0.5 percent gain, followed three straight months of increases. Pending home sales, which lead sales by a month or two, increased 6.0 percent in May.

Contracts fell in the Northeast and the South, but rose in the West and the Midwest.