Beijing unveiled yet another slew of measures on Monday to curb a choking pollution problem, including limiting the number of new vehicles on the roads and closing or upgrading the facilities of 1,200 companies.

China's smoggy capital has tried everything from shutting factories to a massive subway building programme as it battles a severe air pollution problem, but with little apparent effect.

The latest measures are part of a broader plan to reduce the Chinese capital's density of harmful particles in the air by at least 25 per cent by 2017.

"It's a declaration of war against PM 2.5," the Beijing Municipal Environmental Protection Bureau said in a statement on its website, referring to tiny particles in the air that pose the greatest risk to human health.

"The city will work relentlessly to improve air quality."

The Chinese government has been increasingly alarmed by social unrest caused by environmental disasters and threats to publ ic health, often the result of breakneck industrial expansion and mass migration to new cities.

In the newly unveiled measures, Beijing will place tougher restrictions on the number of new vehicles allowed on the roads each year, curbing annual growth to nearly zero.

The government aims to cap the number of vehicles in the city at six million by the end of 2017, compared with 5.35 million by the end of July, according to the official Xinhua news agency.

Beijing also aims to reduce total vehicle fuel consumption by at least 5 per cent from 2012, by promoting the sale of new energy and small vehicles, and encouraging people to drive less frequently, Xinhua said.

Beijing will also restrict the number of vehicles allowed in specific areas during certain times of the day, starting in 2014, it added.

"In order to curb vehicle emissions, we have to introduce a market mechanism to reduce intensity of vehicle use," Xinhua quoted city environmental offici al Li Kunsheng as saying.

Beijing, along with other three cities - Shanghai, Guangzhou and Guiyang - is already subject to new car sales restrictions, while eight more cities plan to follow suit, China's automobile association said in July.

Carmakers turn to other cities

Carmakers including Volkswagen AG, General Motors Co, Toyota Motor Corp and Ford Motor Co have all said they are shifting their attention to China's lower-tier cities, as growth in big cities such as Beijing and Shanghai starts to stagnate.

Other measures to be introduced to clean up Beijing's air included ordering 1,200 polluting companies to upgrade or close some or all their facilities in the years to 2016, Xinhua added.

"In regions or industries that fail to meet air pollution reduction targets, no new projects that emit major air pollutants will be given regulatory approval as of 2013," it said.

"Companies who break environmental laws will be banned f rom receiving bank loans, fund-raising through initial public offerings and value-added tax breaks starting this year."

Smoke from factories and heating plants, winds from the Gobi Desert and fumes from millions of vehicles can combine to blanket the city in a pungent shroud for days. English-speaking residents sometimes call the city "Greyjing" or "Beige-jing".

Reuters