The second plan to cap the leaking gas well in southwest China's Chongqing Municipality was again suspended late Wednesday night, according to the headquarters dealing with the accident.

Emergency workers started implementing the second plan to seal off Luojia No. 2 well in Gaoqiao Town of Kaixian County at around 6 p.m. Wednesday, but the operation was suspended at 10 p.m. because unknown conditions had arisen from deep down the well, said a source with the headquarters.

The situations are very complicated since there are leakages down the over-2000-meter-deep well, from the pipeline and around the well, said experts dealing with the accident.

The gas field in Gaoqiao is one of largest in the country, where the gas pressures and sulphur content are among the highest.

The second plan had previously been postponed from Tuesday to Wednesday due to the complicated situations around and down the leakage site. The first attempt to shut down the well failed on Monday.

Li Yizhong, director of the State Administration of Work Safety, arrived at the site early Wednesday to oversee the operations. Wang Yang, secretary of the Chongqing Municipal committee of Communist Party of China, and Mayor Wang Hongju arrived at the site on Tuesday to direct the capping efforts.

Workers have been monitoring the air and water quality within one kilometer of the leaking well, reporting the results hourly.

More than 10,000 residents living within one kilometer of the well have been evacuated and over 4,000 students have been affected as classes were suspended at six schools following the gas leak.

The leak was discovered at the well belonging to the China National Petroleum Corporation's Sichuan Provincial Petroleum Administration Saturday morning. No casualty has been reported.

The gas well is within the vicinity of the Luojia No. 16H Gas Well, where a deadly gas blowout killed 243 people on December 23, 2003.

Following the 2003 gas blowout, Ma Fucai, former general manager of CNPC, resigned; six people were jailed for dereliction of duty, including the head, engineers and technicians of the ill-fated well.