China plans to remove?six million high-emission vehicles off the road this year to reduce pollution, the Ministry of Environmental Protection said on Tuesday.

More than 2.4 million vehicles will be taken off roads in the municipalities of Beijing, Tianjin and Hebei Province, along with another four municipalities and provinces along the Yangtze River Delta and Pearl River Delta, according to the ministry.

An action plan, issued by the General Office of the State Council, China's Cabinet, has been distributed to local authorities, according to the ministry.

A ministry spokesman on Tuesday urged local authorities to formulate stimulus policies and enforce stronger laws to eradicate such vehicles.

Pollutants discharged by cars are blamed as a leading cause for choking air pollution and lingering smog in parts of the country. In Beijing, for example, cars discharged more than 30 percent of the capital's PM 2.5, a particulate matter with a diameter less than 2.5 micrograms that caused hazardous smog. In Shanghai, the percentage is about 25 percent.

China has been the world's largest auto market and producer for five consecutive years, with production and sales both exceeding 20 million units for the first time in 2013. Official statistics showed car ownership increased to 137 million last year.

"Huangbiaoche", or "yellow-label cars", referring to vehicles that fail to meet national emission standards, account for about 10 percent of the country's total number and emitted about half of all car pollutants, official statistics showed.