China's media has urged the government to take action to tackle air pollution, which has blanketed parts of the country at dangerous levels in recent days.

China's media are under tight Communist Party control and usually steer clear of controversy, but news organisations are free to report on pollution, partly because it cannot be hidden from the public.

Air quality in Beijing was far above hazardous levels over the weekend, reaching 755 on an index that measures particulate matter in the air with a diameter of 2.5 micrometers.

A level of 300 is considered dangerous, while the World Health Organisation recommends a daily level of no more than 20.

Thick smog shrouded the capital at the weekend, cutting visibility and sending many people out to buy face masks in an attempt to protect themselves.

It was the worst recorded air pollution in the capital, according to Zhou Rong, climate and energy campaigner at Greenpeace.

Today was again gloomy but the pollution index stood at 321 in the afternoon, according to widely followed data collected by the US Embassy from its own measuring device.

"How can we get out of this suffocating siege of pollution?" the People's Daily, the official newspaper of the Communist Party, said in a front-page editorial.

"Let us clearly view managing environmental pollution with a sense of urgency."

The Global Times newspaper said the foul air "shocked locals ... triggering calls from the public to shift the country's development model away from the previous fixation on economic growth".

It said heavy smog was hanging over most of the north China plain.

Cars pump out much of the pollution, which fills the air on cold, windless days.

Many people burn coal for heat in the winter, and this winter is the coldest in years.

The China Daily blamed Beijing's tall buildings for trapping the pollution.

"The high-rises are too densely built and block the dirty air from dispersing," it said.

Many other cities showed alarmingly high pollution over the weekend. About half of 74 cities monitored for air quality showed severe pollution, the People's Daily said.

Particulate matter with a diameter of 2.5 micrometers, known as PM2.5, can cause cardiopulmonary disease, lung cancer and acute respiratory infection, according to the Journal of Toxicology and Environmental Health.

Authorities advised citizens to stay indoors and ordered government car fleets to cut back driving.