Region-specific Visa Restrictions
There are special rules to obain a visa to the Special Administrative Region of Macao that exempt only a few countries' nationals. Residents of the "mainland" of China have had great difficulty in obtaining a visa to go to Macao (also spelled Macau), due to what is termed an informal policy. This may have been done to prevent money laundering, but by August 2010, the policy has hurt the Macau economy, especially its casinos.
The Australian government warns that:
The Chinese government does not recognise dual nationality and will not allow consular access by the Australian Embassy or Consulate to Australians detained by Chinese authorities if they have entered China on a Chinese passport, a Hong Kong or Macau identity card or any non-Australian foreign passport. ... Hong Kong and Macau are Special Administrative Regions (SAR) and have separate visa and entry administration. Travellers who exit mainland China to visit Hong Kong or Macau may require a new Chinese visa to re-enter mainland China. Travellers with a single entry visa for China should be particularly diligent to this requirement. Some travel permits, issued in Hong Kong or at Hong Kong-Macau-Chinese mainland border crossings, are valid for limited travel to designated areas only such as Shenzhen, Zhuhai or other areas in Guangdong Province. It is illegal to use these permits to travel to other parts of China. Travellers should carefully check the details on their visa. —"Travel Advice for China", Government of AustraliaRead more about this topic: Visa Policy Of The People's Republic Of China