BEIJING, China (CNN) -- Chinese officials say they have warned Russia about a chemical spill that has disrupted life in the city of Harbin and will reach Russia in about two weeks.A toxic benzene spill has caused the stoppage of water service in Harbin and sparked widespread unease among its 9 million residents, mainly because of the length of time it took government officials to issue information regarding the potential health threat.The benzene was spilled into the Songhua River on November 13 by an explosion at a petrochemical plant in an adjacent city on the river. The blast killed five people and forced the evacuation of tens of thousands of others.The 80-kilometer (50-mile) slick traveled down stream, and by Thursday was in Harbin. Benzene, used in gasoline, is a cancer-causing substance.The contaminated water reached Harbin's water supply inlet at about 5 a.m. Thursday local time (2100 GMT), and entered river sections across the city's urban areas, according to the Heilongjiang provincial environment protection bureau, the state-run Xinhua news agency reported.Chinese officials said the polluted water would reach the Heilongjiang River, called the Amur River in Russia, on the Sino-Russian border in around 14 days judging from the current flow speed, Xinhua reported.Zhang Lijun, deputy director China's State Environmental Protection Administration, was quoted as saying that some of the 100 tons of pollutants had been absorbed because the density of the pollutants had dropped markedly.Zhang, addressing a press conference in Beijing Thursday, said a chemical plant run by the China National Petroleum Corp.'s Jilin Petrochemical Company should be held responsible for the pollution. CNPC deputy general manager Zeng Yukang apologized for the accident and said CNPC would help with the cleanup, Xinhua reported."China is very concerned about the possible hazards to Russia and has informed its neighbor several times of the pollution," Foreign Ministry spokesman Liu Jianchao said at a press conference. "Both have pledged to cooperate closely to handle the pollution."Russian officials, however, have said China dragged its feet in communicating about the potential health hazard. Moscow has issued a statement to its neighbors asking them to communicate about matters potentially affecting Russia in a "timely manner."Harbin has cut off its water supply for at least four days, and has trucked in 700 tons of bottled water. New wells are being drilled to make up for the shortage. Schools in Harbin, the capital of Heilongjiang province, have closed and hospitals were put on standby to deal with any medical emergencies, although none were immediately reported.Besides the potential for an environmental disaster, the incident has turned into a public relations disaster as well for the Chinese government, which until the past two days had not given residents timely information about the approaching toxic chemicals. In an effort to appease the public, government officials, in a rare turnaround, began offering hourly updates.Officials have estimated the slick may pass Harbin in about 40 hours, but residents -- who scrambled to save water in pails and bathtubs as well as cramming grocery stores to stock up on bottled water -- remained worried about long-term health effects, and many were taking no chances."We promise to resume the water supply after four days," said Zhang Zuoji, provincial governor. "I think the quality will be no problem, because our monitoring department will take a close look at water quality."Zhang offered to drink the first mouthful of water himself, but concerns persisted that the threat could last longer than four days.Others worried about how the threat could affect Harbin's tourism industry. People flock each year to the city's Ice Festival to see sculptures carved out of ice.