Home prices in the U.S. continued to rise steadily in December 2017 at an annual rate of 6.3% from a downwardly revised 6.1% in November 2017, according to S&P CoreLogic Case-Shiller Indices' report.

The 10-city composite remained flat month over month but rose 6.0% annually. The 20-city composite increased 6.3% year over year, down from 6.4% in the previous month.

Home prices in Seattle rose at an annual rate of 12.7%, the largest gain among the 20 cities covered by the index. Las Vegas followed with an 11.1% increase and San Francisco with a 9.2% increase.

David Blitzer, managing director and chairman of the index committee at S&P Dow Jones Indices said the last few months showed signs that gains in housing may be leveling off, with existing home sales falling in December 2017 and January, and pending sales of existing homes flat over the last several months.

"It is too early to tell if the housing recovery is slowing," Blitzer said. "If it is, some moderation in price gains could be seen later this year"

Meanwhile, the Federal Housing Finance Agency said the U.S. house prices edged up 1.6% in the fourth quarter of 2017. The seasonally adjusted monthly house price index was up 0.3% in December 2017.

House prices climbed 6.7% from fourth quarter 2016 to fourth quarter 2017, the agency added.

S&P Dow Jones Indices and S&P Global Market Intelligence are owned by S&P Global Inc.