Beijing will temporarily reinstate measures taken during the Olympics and ban cars on alternate days - depending on whether their licence plates are odd or even - if pollution levels rise to extreme levels, the China Daily newspaper said.

To protect public health over the long term, the city wants to raise the number of days when air quality is good, and will institute 'more stringent measures when conditions are extremely unfavourable', said Mr Du Shaozhong, deputy director of its environmental protection bureau.

Work would also be suspended at construction sites and high-polluting factories during extremely polluted periods, the newspaper said.

The restrictions will be imposed only if the air pollution index reaches 300 points, a threshold far above the city's normal air-quality level, it said.

The driving bans imposed during the Olympics allowed Beijing's 17 million residents to enjoy clear blue summer skies. The city recorded its lowest August pollution levels in 10 years. Since then, newspaper editorials have called for the measures to be extended.

Last month, city officials announced they would introduce some traffic restrictions for a six-month trial period. At the start of this month, they took nearly a third of the city's government vehicles off the road.

Starting next week, the remaining government cars, together with privately owned vehicles, will be banned from the roads one day a week on a rotation basis according to licence plate numbers. The rules will be in effect till February, but will not apply on weekends.

On Thursday, the pollution index was at 47 points. Levels of 51 to 100 are considered moderate; anything above 100 is harmful to children and the elderly.

During the Olympics, the level dropped to as low as 17 points after reaching nearly 100 just a day before the opening ceremony, according to the government.

Beijing also plans to introduce more bus-only lanes and subway lines to encourage more people to use public transport during rush hours, reported China Daily.

'The introduction of fees for the use of certain roads during peak hours must be looked at too,' said Mr Guo Jifu, director of the Beijing municipal transportation development research centre.

ASSOCIATED PRESS