PetroChina's share price fell yesterday after the mainland environmental watchdog said it should take responsibility for water contamination caused by the explosion at a petrochemical plant run by its Jilin subsidiary, raising concerns about legal claims against the mainland oil giant. A company spokesman would not comment on how China's largest oil firm might deal with potential lawsuits from people affected by the 100 tonnes of toxic benzene released from the factory. 'We are still investigating the incident and assessing the damage,' he said. The public was informed about the contamination by the government only nine days after the disaster, while PetroChina's Jilin Petrochemical subsidiary had told state media the benzene would disintegrate in water and was not harmful. Monetary claims resulting from the blast, which killed at least five people, are likely to be small relative to PetroChina's annual profits of more than 100 billion yuan. PetroChina's shares fell 2.41 per cent to $6.05 yesterday. According to PetroChina's filing to the New York Stock Exchange, where its shares are listed, it has no third-party-liability insurance coverage against claims relating to personal injury, death or damage to property and the environment arising from accidents. PetroChina said it had launched safety initiatives at its companies and sent drilling teams from the Daqing oilfields to drill water wells in Harbin , where water supply from the contaminated Songhua River was cut off. 'PetroChina will continue its follow-up work after the accident [and] hold the personnel accountable who caused the accident,' it added.