Beijing will further expand its public transport network in a bid to relieve the city's clogged roads, a top city official said yesterday.

Liu Qi, Party secretary for the capital, vowed that the city will keep fares low and provide a more comfortable and convenient passenger experience.

The city aims to have 50 percent of residents using public transport - from the current 30 percent - Liu said during a group discussion at the ongoing Party Congress. He did not offer a timetable for the increase.

The 2008 Olympic host city has sought to promote public transport, ensuring it remains affordable while new metro lines open across the city. A new north-south route opened on October 7 and three other new subway lines will be added next year.

Metro fares in the city were cut by more than 30 percent this month, while bus fares were slashed by more than 60 percent in January. A one-way metro ticket now costs only 2 yuan (27 cents), about the price of a can of coke, no matter how long the journey.

The new line has had an immediate positive effect. The number of subway passengers has increased by 46 percent since it opened, Mayor Wang Qishan revealed during the discussion.

Public transport not only reduces road congestion but could also improve air quality.

Beijing had 3.06 million registered vehicles by the end of July, producing a significant part of the city's air pollution.

In August, Beijing held a four-day air quality exercise, during which half of the vehicles were ordered off the roads. The exercise saw the amount of pollutants fall by 5,815.2 tons.

The exercise was part of a Green Olympics campaign, which also includes the relocation of Shougang Group, one of China's major steel mills, a reduction in coal use and heavy investment in water recycling systems.

"Beefing up efforts to fight air pollution is not only for the sake of the Olympics, but also to make Beijing more suitable for living," Liu said.