The toughest anti-smoking legislation in China's history came into effect Monday in Beijing, with unprecedented fines and a hotline to report offenders following fears of weak enforcement.

The law makes smoking in offices, restaurants, hotels and hospitals illegal, with venues where the ban is flouted liable to fines of up to 10,000 yuan ($1,600).

Venues which repeatedly ignore the law could have their licenses revoked, while individuals caught smoking in specified areas could be fined as much as 200 yuan.

As well as indoor smoking, the law prohibits lighting up in some open-air spaces close to schools, hospitals, and sports venues.

Despite a government awareness campaign that saw posters detailing the law displayed in restaurants and offices around the city, many say it will be difficult to implement.

Nightclubs had been singled out as a potential problem area, Zhang Jianshu, president of the Beijing Tobacco Control Association, told the China Daily newspaper.

"The key lies in the business owners," the paper quoted Zhang as saying Monday. "They have the responsibility to ensure no smoking within their establishments."

Various parties -- the police, building managers, tenants and health inspectors -- have been called on to implement the ban, but the law "fails to make clear who is ultimately responsible, thus leaving the possibility that they will pass the buck to each other", state-run newspaper Beijing Youth Daily pointed out.

The law -- limited to the capital -- is not China's first such effort.

A similar nationwide measure was passed in 2011, albeit without financial sanctions, but implementation was lacklustre.

Environmental and safety laws in China are often openly flouted because of limited official oversight, or corruption in the form of bribes to law enforcers.

Cigarettes remain cheap, with packs often costing less than 10 yuan, and some Chinese experts say the Beijing law still does not go far enough.

"The new regulation should require tobacco producers to print a warning on cigarette packages," Jiang Huan, vice-director of the Chinese Center for Disease Control and Prevention, was quoted as saying by the China Daily.

Health commission inspectors will be in charge of enforcing the law, carrying out spot-checks and acting on tip-offs from the public.

Posters in the capital advertise a hotline number for tip-offs, and the city government has launched a social media account allowing observers to upload images of smokers caught in the act.

One barrier to imposing similar measures across the country is the continued clout of China's state-run tobacco industry, which provides the government with colossal amounts of money -- 911 billion yuan in taxes and profits in 2014, an increase of 12 percent year-on-year.

China's tobacco regulator shares offices and senior officials with the state-owned China National Tobacco Corp, which is by far the world's biggest cigarette producer and has a near monopoly in the country.