Sales of new U.S. single-family homes dropped in April as prices surged amid a tight supply of houses, which is threatening to slow the housing market momentum.

New home sales dropped 5.9% to a seasonally adjusted annual rate of 863,000 units last month, the Commerce Department said on Tuesday. March's sales pace was revised lower to 917,000 units from the previously reported 1.021 million units. Economists polled by Reuters had forecast new home sales, which account for a small share of U.S. home sales, at a rate of 970,000 units in April.

New home sales are drawn from a sample of houses selected from building permits and tend to be volatile on a month-to-month basis. Sales surged 48.3% on a year-on-year basis in April. Monthly sales declined in the populous South, the Midwest and Northeast, but rose in the West.