Evacuees are returning home, six days after fleeing their villages

Thousands of people are returning to villages in southwest China affected by a gas explosion which left at least 233 people dead.

A total of 64,000 people fled the remote, mountainous area after a natural gas well burst last week, releasing a high concentration of natural gas and sulphurated hydrogen.

On Monday, some 20,000 people were returning to homes within five kilometres (three miles) of the gas field in the town of Gaoqiao near Chongqing, state television reported.

DEADLY GAS Mix of natural gas and sulphurated hydrogen Left acid burns on eyes, skin and lungs At least 233 people dead In pictures

Many had been sleeping on floors in schools and government buildings in nearby towns.

Other residents had already returned to outlying areas on Sunday, after engineers had pumped 480 cubic metres of concrete into the burst gas well to seal it.

"Air and water in most villages are safe now and evacuees can begin returning," said Zhang Shaozhi, the local director of environmental protection, quoted by the official Xinhua News Agency.

But some villages still showed "high concentrations of poisonous gas" which might delay the return of residents living closest to the gas field, said Xinhua.

The government said it has set up five monitoring stations around the gas field to continue checking the air and water.

The number of people known to have died rose to 233 after an additional 35 bodies were found on Sunday, according to state media. Most of the deaths and injuries were caused by gas inhalation.

Survivors described the gas as an acrid black fog that clung to the ground, choking them and burning their eyes and skin.

Investigation

Medical workers have disinfected eight villages close to the site of the leak and removed almost 4,000 animal carcasses which covered the area.

"I want to clean up my house and count my losses because we can't smell the fumes now," one farmer told Xinhua.

China is notorious for its dangerous working conditions in factories and coalmines, but this is reported to be its worst industrial accident.

The explosion took place at a natural gas field operated by the state-run oil company China National Petroleum Corporation, which as of Monday had not released any statements of condolence or responsibility for the disaster.

Now that the well has been blocked, an investigation has been launched which will decide if the company is responsible.

Many of the confirmed dead are children or elderly people who were unable to flee after the explosion.

Those who did not escape in time - including farm animals and fish - suffered burns to their skin and lungs from the gas.