Vehicles drive on Beijing's Fourth Ring Road amid heavy smog, Oct 24, 2014. [Photo/Agencies]

SHANGHAI - Chinese Vice Premier Zhang Gaoli ordered a temporary shutdown of factories to ensure air quality during a meeting of Asia-Pacific leaders in Beijing next month.

It is the strongest measure yet to curb pollution for the Nov 7-11 meeting in the capital, which has been enveloped by heavy smog over the past few days.

On Friday, Beijing extended a yellow alert for severe smog and air pollution, with PM2.5 at more than 500 micrograms per cubic meter. The smog is not expected to disperse until Saturday evening.

Zhang told officials that ensuring air quality during APEC is the "priority of priorities", although the task will be a "tremendous pressure and challenge" given dropping temperatures and the start of the coal burning season in northern China.

Local authorities were said to ensure that high-polluting enterprises - such as power, construction, steel making, petrochemicals and coking - in Beijing and its neighborhood are suspended or reduced, and construction work halted.

Air pollution control in the notoriously smoggy Beijing-Tianjin-Hebei region this winter and spring next year is a top priority, and authorities must take measures to cut pollution as a result of coal burning.

Zhang also said vehicle controls must be strictly enforced and residents should be encouraged to take public transportation during the meeting, the report said.

In an effort to ease traffic congestion and curb pollution, Beijing has already announced that public workers in the capital will be given six days off during the APEC meeting.