Smog-hit China is set to pass a new law that would give Beijing more powers to shut polluting factories, punish officials and even place protected regions off-limits to industrial development, scholars have said.

Long-awaited amendments to China's 1989 Environmental Protection Law are expected to be finalized later this year, giving the Ministry of Environmental Protection (MEP) greater authority to tackle polluters.

While some details of the fourth draft are still under discussion, it has been agreed that the principle of prioritizing the environment above the economy will be enshrined in law, according to scholars who have been involved in the process. The fourth draft is due to be completed within weeks.

"(Upholding) environmental protection as the fundamental principle is a huge change, and emphasizes that the environment is a priority," said Cao Mingde, a law professor at China University of Political Science and Law who was involved in the drafting process.

The first change to the legislation in 25 years will give legal backing to Beijing's newly declared war on pollution and formalize a pledge made last year to abandon a decades-old growth-at-all-costs economic model that has spoiled much of China's water, skies and soil.

Cao cautioned that some of the details of the measures could be removed as a result of bureaucratic horse-trading. The MEP has called for the law to spell out how new powers can be implemented in practice, but the National Development and Reform Commission (NDRC), the country's top economic planning agency, prefers more flexible principles.

"There is a usual practice when everyone is unable to come to a complete agreement — we first put an idea into the law and draw up detailed administrative rules later," Cao said.

The environment ministry did not respond to a request for comment on its role in the drafting process and the content of the new amendments.

In the absence of legally enshrined powers, the ministry has often made do with one-off national inspection campaigns to name and shame offenders, as well as ad hoc arrangements with local courts and police authorities to ensure punishments are imposed and repeat offenders shut down. It has also stretched existing laws to its advantage.

Last year, it began to use its powers of approval over environmental impact assessments, which are mandatory for all new industrial projects, to force powerful industrial firms such as Sinopec and the China National Petroleum Corporation to cut emissions at some of their plants, threatening to veto all new approvals until the firms met their targets.The new law would give the ministry the legal authority to take stronger punitive action.

"The environment ministry could only impose fines and management deadlines," Cao said. "Now we can close and confiscate them. It's an important right."

Cao said the final draft was also likely to impose an "ecological red line" that will declare certain protected regions off-limits to polluting industry.

Experts have welcomed commitments to improve transparency and compel polluters to provide comprehensive and real-time emissions data. Criminal penalties will also be imposed on those found guilty of trying to evade pollution monitoring systems.

"The provisions on transparency are probably the most positive step forward. These include the requirement that key polluters disclose real-time pollution data," said Alex Wang, expert in Chinese environmental law at UCLA. Wang said he had not seen the later, nonpublic drafts of the legislation.

For nearly two years, scholars, ministries, local governments, companies and officials have been debating the changes to the environmental protection law.

UCLA's Wang said the ultimate success of China's war on pollution would be determined not by symbolic new legislation but by specific targets and guidelines now being imposed on local governments.

"Many people point to China's laws as a sign of the government's concern about the environment," he said. "But changes in bureaucratic targets are a more direct indication of changing priorities and can tell us whether Beijing means business."