A THOUSAND Chinese soldiers were drafted in this weekend to stack 300 tons of filters at a waterworks in the industrial city of Harbin in a desperate effort to solve a pollution crisis that has cut off water to more than 3m people.

Mains supplies were shut off for a fifth day as a 50-mile slick of toxic chemicals in the Songhua River slid past the city a fortnight after an explosion at a chemical plant upstream poured 100 tons of benzene and other cancer-causing pollutants into the river.

The disaster has become political as well as environmental: there was a cascade of public fury over the disclosure that Communist party officials covered up the leak on November 13, then lied to the citizens of Harbin, setting off mass panic and an exodus from the city.

A diplomatic catastrophe is looming, too. The slick is now oiling its way down the slowly freezing Songhua to the border with Russia, where it joins the mighty Heilongjiang, the Black Dragon River, then flows past the Siberian city of Khabarovsk. And the Russians have only just been told.

Yesterday, Harbin’s party chief, Du Yuxin, appealed for patience as the soldiers finished their task and engineers prepared to flush river water through the filters. He promised that the taps would be flowing again by tonight.

Meanwhile, schools were shut, shops stocked up on emergency supplies of bottled water and some hotels closed their doors.

As winter temperatures fell sharply in a city renowned as the coldest in China, its poorest residents — those who could not afford to cram onto outbound planes and trains — huddled in queues for water dispensed free by fire tenders and tankers.

“I can’t afford bottled water,” explained Wang Cui Hua, 45, who supports her small son by selling fruit. “My husband has lost his job and we only earn 400 yuan (£28.57) a month.” Water costs 1 yuan (7p) for a half-litre bottle.

Her plight symbolised the decline of Harbin, 600 miles northwest of Beijing. It was once a bustling hub of heavy industry, but many of its 3.8m people have been out of work for years after local state-owned enterprises collapsed under the pressure of economic reform.

The toxic spill, which has caused outrage across China, also dealt a heavy blow to the city’s endeavour to revive its fortunes by attracting investment.

Party security chiefs ordered swift action to rush in water supplies and quell disorder once the disaster became public, fearing that mob scenes in supermarkets and at railway stations could turn into mass protests.

Yet although Chinese media and the internet seethed with indignation, there was only resignation to be found among the poor folk lining up with their buckets under the watchful eyes of plainclothes policemen in a run-down western part of the city.

“The government has told us that the water in these tankers comes from a well and is safe,” said Li Wei Han, 60, a retired worker. “What can we do if we don’t trust the government?” That is the question on many lips after days of excoriating coverage in the Chinese media that was so intense the censors finally ordered journalists late on Friday to stop it.

Widely viewed as China’s worst environmental disaster for years, the spillage is the latest in a long line of incidents that officials have bungled or tried to cover up, from plane crashes to Sars and avian flu.

It started with two explosions in the city of Jilin. An amateur cameraman caught the second detonation on video as clouds of thick, toxic smoke billowed into the clear blue sky above a chemical plant. Five workers died, 70 were injured and 10,000 people were removed from the vicinity.

The plant is owned by Petrochina, a subsidiary of China’s National Petroleum Corporation. Its stock, a favourite of fund managers, is listed in New York and Hong Kong. But it provided none of the corporate transparency of which big Chinese companies like to boast to their foreign investors.

Managers did nothing to warn the public even though they knew the risks. Within a day, technicians found levels of benzene, dianil, nitrobenzene and dimethyl benzene up to 100 times normal levels in the Songhua. Benzene, if ingested by humans, can cause cancers and damage to the liver and kidneys.

Yet as fish died and the contamination drifted downstream, nobody told villagers and fishermen along the 236 miles of the Songhua between Jilin and Harbin. The consequences to their health could be calamitous.

It was last weekend before local government officials in Harbin realised that a toxic wave was heading towards their city – and even then they could not bring themselves to tell people the truth.

“At first they said they would cut off the water for routine work,” said one local resident. “Of course, nobody believed that, so everybody then believed a rumour that an earthquake was predicted. There was panic.”

The government in Beijing has dispatched a team of disciplinary cadres to investigate and has promised punishment.

It could turn the disaster into a salutary example of why China must clean up the environmental devastation that has accompanied its headlong dash for growth.

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