Chinese Premier Li Keqiang vowed on Sunday to hold polluting factories liable for excessive emissions, but he sidestepped a question about the government's censorship of a viral documentary video about the nation's smog crisis.

"Enforcement of environmental laws should not be a cotton swab but a killer mace." Li said at a news conference after the close of China's annual legislature in Beijing.

“The Chinese government is determined to tackle smog and environmental pollution as a whole,” Mr. Li said, according to an account in the New York Times. “But the progress we have made still falls far short of the expectation of the people. Last year, I said the Chinese government would declare war against environmental pollution. We’re determined to carry forward our efforts until we achieve our goal.”

Li's comments come at a time of growing public anger over the degree to which China's rapid industrial growth - and weak regulation of that growth - has fouled air and water in the nation's urban centers.

Chinese Premier Li Keqiang at news conference Sunday folllowing the end of the National People's Congress. Image: Mark Schiefelbein/Associated Press

Partly in response to those concerns, China's government has committed to peaking its carbon dioxide emissions by 2030 at the latest, and increase its share of renewable energy to 20% by 2020. This would involve significantly scaling up clean, renewable power plants and a lower reliance on the dirty coal plants responsible for much of the smog that cloaks Beijing and other cities for days at time.

Li also called upon citizens to recognize their own environmental responsibilities.

"It's a project in which everyone in the society should take responsibility," Li said. "If you cannot change the environment you are in, you can modify your behaviors."

Li's comments on the environment came in response to a question by a Huffington Post reporter about a recent documentary exposé about smog in China, "Under the Dome." The online video drew more than 200 million views in China before being blocked by censors.

Li avoided directly answering the question about “Under the Dome,” but he acknowledged some of the problems raised by the documentary, especially lax enforcement of pollution laws.

“All acts of illegal production and emissions will be brought to justice and held accountable,” he said.

The Hong Kong news site South China Morning Post has a useful list of the topics that Li addressed, avoided and sidestepped during his news conference.

Additional reporting by The Associated Press.