The nationwide ban on smoking indoors in public areas, imposed two years ago, lacks specific regulations on how to enforce the law, health officials from four regions said in a conference in Beijing on Wednesday.

According to a 2011 law - called the Implementation Rules on Regulations on Public Places Sanitation Administration - by the Ministry of Health, smoking is banned in indoor public places, such as restaurants, hotels and movie theaters. Signs must be posted in public places to warn smokers of the ban and workers are obliged to stop any smokers they see.

One drawback, however, is that the ban doesn't define how local health officials should levy fines or mete out punishments for violations.