Chinese police arrested thousands of people suspected of environmental crimes last year, a minister told parliament Monday, while at the same time vowing to get serious about protecting the environment.

Environment Minister Chen Jining told a bi-monthly session of the National People's Congress' standing committee that the number of criminal cases handed over to the police by environmental protection departments in 2014 reached 2,080, twice the total number during the previous decade. More than 8,400 people were arrested, according to a transcript of Chen's address published on the parliament's website.

Facing mounting public pressure, leaders in Beijing have declared a war on pollution, saying they will abandon a decades-old growth-at-all-costs economic model that has spoiled much of China's water, skies and soil.

But forcing growth-obsessed local governments and powerful state-owned enterprises to comply with the new laws and standards has become one of the Chinese government’s biggest challenges.

“When Deng Xiaoping came to power, he decentralized power to the local government to stimulate economic growth. In essence he created a federal system with no checks,” said Jennifer Turner, director of the China Environment Forum at the Wilson Center, referring to the reformist Chinese leader who took power in the 1970s. “Now the Chinese government has been playing catch up. They’ve been trying to create environmental regulations and laws and campaigns to check pollution. In the 1990s, this was a halfhearted check, because the Communist Party and government needed the economy to develop … Now that the pollution is a true threat to economic development, they’ve got to deal with it.”

According to a 2013 report from the World Bank, environmental degradation and resource depletion costs China about 9 percent of its Gross National Income.

Beijing has repeatedly promised to strengthen monitoring and law enforcement, and a new environmental law in force since the beginning of January allows it to impose unlimited fines and jail sentences on repeat offenders.

“The environmental protection amendments were significant in that they said if local governments will not meet the standards, they won’t get money for developing their economy,” said Turner. “So the hammer has been coming down.”

In his speech to congress, Chen said the central government had allocated 9.8 billion yuan ($1.58 billion) in special funds to control air pollution in 2014, which helped "leverage" additional private investment of 300 billion yuan.

Chen added China would aim to cut key air pollutants sulfur dioxide and nitrogen oxide by 3 percent and 5 percent respectively this year, and would work to improve vehicle fuel standards nationwide.

Recognition of an environmental crisis has been building in China over the past few years, particularly since the winters of 2012 and 2013, when smog blanketed cities like Beijing. But Beijing has also cracked down on dissent, leading to an uneasy relationship between the government and environmentalists.

Earlier this year, the government initially allowed the airing of a documentary on air pollution in China called “Under the Dome,” but then, after garnering over 200 million hits and spurring national debate, the video was pulled down, the Wall Street Journal reported. Censors keep a grip on what can be published online, especially if it is seen to undermine the Communist Party.

An English language version of the Xinhua News Agency, the official press agency of China, reported that the national hotline for public reports on polluting enterprises received only 332 tips in the first quarter of 2015.

Al Jazeera with Reuters. Azure Gilman contributed to reporting