Two years ago, Katie Melua had a hit with her song about there being "9 million bicycles in Beijing".

Now, authorities in the city are hoping a new bike promotion campaign will be equally popular and reinforce its status as the capital of the "Kingdom of the Bike".

Following the success of the car reduction test event, which ended yesterday and recorded four consecutive days of Grade II air quality, the government on Saturday unveiled a new bike rental scheme to maintain the momentum.

Under the scheme, 50,000 bikes will be available for rent soon throughout the city. They will cost 100 yuan ($13) for a one-year contract or 20 yuan per day.

Users have to pay a 400- yuan deposit, but this is refunded, less annual rental fees, on return of the bike.

Regular repairs and an old-for-new exchange service are also included in the price.

In recent months, the Beijing government has been running trials of the service in 31 locations across the city.

"It has proved really popular, so it is worth rolling it out across the city," Du Shaozhong, deputy director of the Beijing municipal environmental protection bureau was quoted by the Beijing News as saying.

It is estimated the rental network will cover some 200 locations by the time of next year's Olympics in a bid to ease traffic congestion.

"Bikes have never become outdated in China, and they are even starting to have an impact on cities around the world," Du said.

A China Daily poll found most people were in favor of the scheme, saying it would help reduce pollution and ease traffic congestion.

At the end of 2003, Beijing had more than 10 million registered bicycles.