BEIJING • China's Environment Ministry has named and shamed several cities in the north of the country for not doing enough to cope with smog, state news agency Xinhua has reported.

Large parts of northern China have been blanketed in choking smog this winter, defying repeated government efforts to tackle the problem. Pollution alerts are common, especially during bitterly cold winters when energy demand, much of it met by coal, soars.

The inspection of 18 cities in Beijing, Tianjin and Hebei province by the Ministry of Environmental Protection found several problems in their smog response, including inadequate planning and poor implementation of policies, Xinhua reported late on Sunday.

Hebei's Cangzhou city was criticised for failing to draw up a detailed list for business shutdowns on heavily polluted days, which made it hard to achieve a reduction in emissions, the report said.

The local authorities in Dezhou city did not revise emergency response schemes in time, while Baoding city was well behind in upgrading coal-fired boilers to make emissions cleaner.

Meanwhile, Jiaozuo city did not begin traffic controls by taking vehicles off the road when the city went on red alert for pollution, according to the ministry.

China has a four-tier colour-coded warning system for air pollution, with red being the most serious, followed by orange, yellow and blue.

Several companies in Beijing, Dezhou and Zhengzhou were also criticised for breaching emission rules, according to the report.

China is in the third year of a war on pollution aimed at reversing the damage done to its skies, soil and water after decades of untrammelled economic growth.

Across the country, a total of 720 people were detained and 6,454 held accountable for environment- related wrongdoing last year, according to earlier official information.

REUTERS, XINHUA