Residents now are allowed one trip every three months instead of two months. One of Macau’s biggest sources of customers is Guangdong.

The Hong Kong-based paper said the new policy, which quietly took effect on Oct. 1, seems to be aimed at curbing the outflow of Mainland money and limiting casino development.

U.S. companies with hotel casinos in Macau include MGM Mirage, Wynn Resorts Ltd. and Las Vegas Sands Corp.

Shares of MGM, already pressured by a down market, fell $3.23, or 12.1 percent, to close at $23.56. Wynn lost $6.35, or 7.9 percent, to finish at $73.84. Las Vegas Sands gave up $4.81, or 15.4 percent, to $26.51. A report that China is imposing new visa restrictions for visitors to Macau is taking a toll on U.S. gaming stocks with properties in Asia’s Las Vegas.

The South China Morning Post said Thursday that Mainland authorities have quietly changed the visitation policy for the residents of the southern Chinese province of Guangdong.

The company also was downgraded by an analyst on Thursday.

China’s new visa policy follows several moves to tighten visits to Macau since June. Guangdong residents had been allowed to stay in Macau for seven days once every two months.

Andy Wu Keng-kuong, president of the Travel Industry Council of Macau, told the paper that the visa limits could hurt growth in Mainland visitors.

But he still expects visitor numbers for the year to be up 10 percent from 2007. Visitor arrivals to Macau have been rising by almost 20 percent annually in recent years.