Sarah Liao said China's State Council had approved the network around Guangzhou, the booming metropolis in the Pearl River Delta industrial heartland.

"They have got the planning for an inter-city public light rail approved by the State Council," Liao said. "That is a big step forward. That was argued for at least two or three years."

She said the system would be a boon for air quality in Hong Kong, where pollution has risen to dangerous levels with the increase in motor vehicles across the border.

"We hope in the future that people across the border will be persuaded to use public transport and not to aspire to the ownership of a car," Liao said.

Government research estimates that 80 percent of the pollution that chokes Hong Kong originates from the 77,000 factories and power stations in the delta, dubbed the "world's factory" for the vast quantities of manufactured export goods produced there.

Liao said a large proportion of the smog came from the exhaust pipes of the region's growing fleet of privately-owned cars, which she said had tripled in the past five years to 2.5 million.

She gave no details of what form the Guangzhou light rail system would take, but plans lodged in 2002 called for a 200 billion yuan (24.1 billion dollar) network covering 500 kilometres (310 miles) of track.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.