Almost 3,500 people were evacuated from a remote town in southwest China's Chongqing Municipality on Sunday night after gas leaked from a well, but no casualties have been reported, the local government said on Monday.

The gas leak occurred at 8:00 PM at a deserted hot well in Tongqiao town of Shuangqiao district on the city's outskirts, said a spokesman for the Shuangqiao district government.

He said the local government immediately evacuated all residents within a radius of one kilometer.

An emergency task force was set up Sunday night. Led by experts from China National Petroleum Corporation, it expects to cap the gas leak Monday afternoon.

A preliminary investigation shows the hot well was drilled by a local tourism company in March 2005, with the intention of building a spa. The company deserted the well three months later when no hot springs had been found.

Experts say the deserted well was not properly sealed, and pressure in the well caused the gas to leak.

The gas was confirmed to be a mixture of sulfurated hydrogen and methane. The municipal environment monitoring station detected sulfurated hydrogen in the air around the leakage area Monday morning.

The Chongqing municipal government has instructed the local environment watchdog to tighten monitoring of air and water quality in the area.

A deadly gas leak in Chongqing's Kaixian county three years ago killed 198 people and hospitalized more than 9,000.

Last month, another gas leak in Xuanhan county, about 500 kilometers northeast of Sichuan's provincial capital Chengdu, lasted six days and led to the evacuation of 12,000 people.

(Xinhua News Agency January 22, 2007)