Gambling revenue in Macau, the only place in China where casino gambling is legal, rose 7% in May from the same month a year earlier, government data showed Friday.

The haul was the second-highest in history, but the rate of growth was the weakest in years due to a variety of statistical factors and stress from a weak Chinese economy, analysts said.

Gambling revenue rose to MOP26.08 billion (US$3.26 billion) last month, higher than MOP24.31 billion in May the year prior, showed data from Macau's Gaming Inspection and Coordination Bureau. In the first five months of 2012, it rose 21% from the same period a year earlier to MOP125.4 billion.

Gambling revenue growth has shot up since the end of 2009, but analysts expect the pace to slow in 2012 due to a high base of comparison last year and concern about the sustainability of aggressive growth in VIP play amid liquidity worries in China. The most bearish 2012 gambling revenue growth estimates for the territory hover around 11% compared with growth of 42% in 2011.

May's 7% rise--a sharp slowdown from April's 22%--was also negatively affected by a shorter holiday season this year and casinos' unusual degree of bad luck compared with an unusual degree of good luck in May last year, analysts said.

Sharp year-on-year increases in gambling revenue will also be less likely from May following the May 2011 opening of Galaxy Entertainment Group Ltd.'s (0027.HK) massive new casino resort, analysts said.

Macau is the world's largest gambling center. Last year it earned more than five times the gambling revenue of the U.S.'s Las Vegas Strip.

-By Kate O'Keeffe, Dow Jones Newswires; 852-2802-7002; kathryn.okeeffe@dowjones.com