US house prices showed their first monthly gain in three years in May offering another sign that the stricken residential real estate market is stabilising.

Home prices unexpectedly climbed by 0.5 per cent from April to May, but were off by 17.1 per cent year-on-year, according to the closely watched Case-Shiller index, released on Tuesday. The monthly rise was the first since prices peaked in July 2006, while the annual drop marked the fourth straight month that the rate of decline slowed after 16 consecutive months of record falls.