Several regions in China have failed to take steps to cut smog during a major meeting of global leaders set to start this week in Beijing, the environment ministry said.

To ensure clean air during a prestigious Asia-Pacific Economic Cooperation (APEC) summit, China said it would thin traffic and close hundreds of factories within a 200-km (124-mile) radius of the capital over the period from Nov. 1 to 12.

Sixteen inspection teams from the Ministry of Environmental Protection (MEP) fanned out to Beijing and surrounding provinces and regions this week to check if emergency curbs were being properly implemented.

But many firms had not followed orders to close and many more were still exceeding permitted emission levels, the ministry said in a notice on its website (www.mep.gov.cn) late on Wednesday.

It said one coking firm in the central province of Henan failed to install mandatory real-time monitoring facilities and refused to let inspectors access polluting equipment.

Another coking firm, in northern Shanxi province, was found to have turned off its dust abatement facilities at night, creating a "pungent, choking odor".

The report also drew attention to the widespread failure of firms to meet a requirement to cut emissions by 30 percent over the APEC period.

With weather conditions expected to become less favorable by the end of the week, local authorities face pressure to try to limit smog build-ups during the APEC summit.

Some cities near Beijing are now delaying the provision of mostly coal-fired winter heating until after the end of the meeting, media have reported.

On Tuesday, the ministry summoned the mayor of the city of Anyang in Henan to discuss its implementation problems, saying the city had not supervised or punished polluters vigorously enough, the official Xinhua news agency reported.

China's central government this year declared a "war on pollution", but normally struggles to impose its will on growth-obsessed local authorities. Beijing has since promised to beef up its powers and monitoring capability.

Local officials are still making economic growth their main priority, rather than environmental protection, a Chinese parliamentary report revealed recently.

In mid-October, the MEP criticized cities in the industrial province of Hebei for not taking emergency measures during a heavy build-up of smog that engulfed Beijing.