Harbin turns off taps indefinitely while blaming blast at upriver chemical plant Water supplies in Harbin , home to more than 3 million people, were cut off last night and will not resume 'until further notice'. The city government of Harbin, capital of Heilongjiang province , warned of a pollution threat to the water supply, which is drawn from the Songhua River. It said an assessment by the Heilongjiang Environmental Protection Bureau found the river had been contaminated by chemicals released by a massive explosion at the Jilin Petroleum and Chemical Company plant in Jilin city last week. 'In order to safeguard water safety in the urban districts, the municipal government has decided to provisionally stop supplying water to the public water network,' the government said in a statement posted on its official website late last night. 'At present there is no sign of any abnormalities along the Songhua River in the Harbin section, but the environmental protection agency expects that upriver pollution could appear in the coming days.' The November 13 explosion at Jilin city's No 101 Chemical Plant, which produced highly toxic benzene, killed at least five people and forced the evacuation of more than 10,000 nearby residents. Heilongjiang Vice-Governor Li Zhanshu told a meeting last night that the first of the contaminated water, which was believed to extend for 100km, was expected to arrive at Harbin at midnight, CCTV reported. The mains water supply plant would close at 8pm. Successive city government announcements since Monday sparked panic in the city, with residents rushing to supermarkets and stalls to buy water. Shi Wenqing, a vice-mayor of Harbin, said the government had been allocated water from neighbouring cities. More than 2,000 tonnes arrived overnight on Monday and the city would also borrow equipment from the Daqing Oil Field and drill 55 new wells. The city's mineral and distilled water companies had also been ordered to operate at full capacity. The 1,927km-long Songhua River winds through more than 30 cities and towns in the nation's northeast. None of them has announced the suspension of water supplies. The Jilin Petroleum and Chemical Company yesterday denied that last week's explosion was the source of the contamination. A spokesman said it had not found any abnormalities in daily water tests. 'We have Asia's biggest sewage treatment plant ... [we] won't release unprocessed water,' he said. Chan King-ming, an associate professor of biochemistry at Chinese University, said the contamination could be a result of a leakage of chemicals stored at the factory. 'Benzene should be reduced to a harmless form if it's completely combusted. But the factory could have stored other chemicals containing phenyl that are toxic and leaked after the explosions,' he said. Professor Chan said prolonged contact with benzene and chemicals with phenyl could lead to hepatitis, urinary tract diseases and possibly cancer. The city government released at least three versions of notices about the suspension of water supplies over the past two days. The first, issued on Monday night, said water supplies would be cut for four days due to maintenance work on the supply system. That announcement led to widespread rumours and media reports of a possible earthquake and chemical contamination. In a second notice released yesterday morning, the government admitted that supplies would be cut for four days because of fears of chemical contamination from the Jilin explosion. Last night's announcement did not give a time frame for the suspension, arousing speculation that it could last for more than four days. Last night, the Harbin Education Bureau released a statement saying all classes at schools would be suspended until Wednesday next week, indicating that supplies could be disrupted for longer than expected and the contamination damage might be more extensive than previously suggested.