China began Thursday to lay tracks for the first high-speed passenger line in its western region, which will ultimately shorten trips between the ancient capital of Xi'an and Beijing to four hours from the current 11.

The 500-km line linking Xi'an in northwestern Shaanxi Province with Zhengzhou in central Henan will run at up to 350 km per hour.

"When it becomes operational at the end of this year, a ride between the two cities will take less than two hours compared with the present six," said Li Hengman, deputy manager of the Zhengzhou-Xi'an Railway Company, operator of the 10.3-billion-US dollar project.

He said the track-laying would be completed by June 10 and the railway was scheduled to be operational on December 28.

Construction began in late 2005. It involved building tunnels in the craggy mountains and reinforcing the loose, sandy earth to support tracks and trains on the loess plateau.

The new route will connect to trunk railways including the north-south Beijing-Guangzhou Railway, while a trip from Shanghai to Xi'an will take only five hours compared with the current 15.

China's first inter-city express railway, the Beijing-Tianjin line running at more than 300 km/hr, opened in August. A trip takes 30 minutes.

Last month, China launched two 250-km-per-hour inter-city passenger lines, one connecting Hefei, capital of eastern Anhui Province, with Wuhan in central Hubei Province and the other, linking Shijiazhuang city near Beijing with Taiyuan in Shanxi Province.

The Beijing-Shanghai high-speed railway will be completed by 2012 and halve travel time to about five hours.