China has been rocked by a hard-hitting film made by a former state TV news anchor which links her baby's tumour to the country's terrible air pollution.

Chai Jing's investigative documentary - which has already attracted unprecedented attention from the country's officials - explores the controversial topic of smog in China, one of the most widespread issues in the state.

In the opening scene of the documentary, Ms Chai tells the story of her daughter, who was diagnosed with a benign tumour before her birth in October 2013.

The 39-year-old goes on to report how a number of newborn babies in China have contracted pneumonia without even leaving home.

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Young victims: Chai Jing, 39, has made a hard-hitting film, exploring the controversial topic of smog in China, one of the most widespread issues in the state

Motherly love: In the opening scene of the documentary, Ms Chai tells how her daughter was diagnosed with a benign tumour before her birth in October 2013

The film also features an interview with Wang Huiqin (pictured), 6, who lives in highly industrialised Shanxi Province and says she has never seen stars or blue skies

Although Ms Chai does not explicitly link her daughter's tumour to China's air pollution, the film - the first to probe the topic in such depth - has prompted public speculation that the two are connected.

It has already been watched by some 200million people and has sparked a firestorm of public criticism over the government's failure to act on the issue in a timely manner.

In the 144-minute film, Ms Chai, a former anchor at China Central Television, the Communist Party's mouthpiece, tells how she made the documentary to tell her daughter 'what is smog, where smog comes from and what we shall do with it'.

She explains how she found herself pregnant in January 2013, when 25 provinces and cities in China were blanketed by heavy smog.

She then gave birth in October 2013, when her daughter had already been diagnosed with a benign tumour.

The diagnosis led to Ms Chai quitting her job at the beginning of last year so she could focus on taking care of her daughter.

It was during that period that she began making the film, entitled Under the Dome, she explains.

Enveloped: Most cities in China, such as Beijing and Shanghai (pictured), face serious air pollution issues

Price for industrialisation: China burns a large amount of petroleum and coal, two major causes of pollution

The film was distributed to various video websites in China on February 28. It received 117 million views in the first 24 hours, according to Tencent.

Ms Chai's daughter is no longer unwell. But she says in the film that she only took her daughter outside when air quality in Beijing was marked excellent or good.

The rest of the time she had to lock her daughter at home 'like a prisoner', she claims.

She adds that 175 days during 2014 were graded as polluted in Beijing.

The film also includes an interview with a six-year-old girl, Wang Huiqin, who lives in Shanxi Province, a heavily industrialised area in central China.

The girl tells Ms Chai in the interview how she has never seen stars, blue skies or white clouds in her life.

Stardom: Ms Chai is a highly recognised anchor and investigative journalist in China. She is also a best-selling writer

Controversy: Although Ms Chai does not explicitly link her daughter's tumour to China's air pollution, the film - the first to probe the topic in such depth - has prompted public speculation that the two are connected

China's cities are often hit by heavy pollution – in the form of smog – caused by burning a large amount of petroleum and coal.

The film has already been widely backed by the Chinese public, as well as a number of officials.

Chen Jining, the newly appointed minister of environmental protection in China, was quoted in an article on People's Daily as saying: 'I want to thank her. She has wakened up the public to pay attention to the environment from a public health perspective.

'I think (she is) worth our respect.'

Self-protection: A girl puts a mask on her dog in Shijiazhuang, capital of north China's Hebei Province, during a smog attack

Fake sunrise: An LED screen on the Tiananmen Square shows what a sun-rise looks like in heavily polluted Beijing

And Gao Mingyong, a senior media commentator in China, wrote on ifeng.com: 'Under the Dome is the best example of self-initiated media which can represent the logic of the internet, but its significance is far more than this.'

Ms Chai financed the making of the film by herself which cost $160,000.