Mainland authorites have quietly extended the clampdown on Guangdong residents visiting Macau. They are now limited to one trip every three months to the casino boom town, travel agents say. The change, effective yesterday, follows several rounds of tightening since June which have slowed Macau's tourism growth. It means a Guangdong resident visiting Macau must wait three months before applying for another permit. Until Tuesday, residents were allowed a seven-day Macau trip once every two months. Secretary for Social Affairs and Culture Fernando Chui Sai-on said the government had yet to 'gather accurate information' about any new travel restriction. Guangdong is Macau's biggest source of punters. Like some of the travel curbs previously aimed at Macau, the new measure appears to be an unwritten policy. Travel agents in Guangzhou and Shenzhen said they had been informed of it by immigration officials. Zhang Yao, a manager at China Travel Service in Guangzhou, said the number of city residents visiting Macau had been falling and looked set to decline further. 'People joining Macau tours in September have dropped by nearly half [compared to August],' Mr Zhang said. 'There used to be more than 10 buses a day taking Guangzhou residents to Macau but now there are only about three.' Like Mr Zhang, Wang Qi, a manager of Shenzhen Comfort Travel Service, said she had learned about the new restriction from immigration authorities. From June 1, Guangdong residents were restricted to visiting Macau once a month instead of once a fortnight. From July 1, they were restricted to visiting once every two months. Since September 1, mainland travellers to Hong Kong have had to get a separate permit to visit Macau. Previously, it was possible to visit both cities on a Hong Kong permit. Andy Wu Keng-kuong, president of the Travel Industry Council of Macau, said the move could stall growth in mainland visitors, but predicted full-year visitor numbers would still be up 10 per cent on 2007. Macau's visitor arrivals have been growing at nearly 20 per cent annually in the past few years. Despite the imposition of restrictions in June, casino revenue rose 42.2 per cent year on year to 9.2 billion patacas in July. In August, revenue was up 44 per cent. Mainland visitor numbers in July were up 29.9 per cent year on year. In August they were up 10.9 per cent. Political commentator Larry So Man-yum said the new travel curbs indicated Beijing was serious about putting the brakes on Macau's casino development and limiting the outflow of mainland money.