PetroChina Co said it had a 'guilty conscience' as a result of a toxic spill in northeastern China and it vowed to work with authorities in the clean up and an investigation...Nowhere in its release did PetroChina say specifically that it was legally responsible for the blast, however. PetroChina's state-run parent company China National Petroleum Corp (CNPC) said earlier today it has an obligation to solve the water contamination problems caused by the explosion, the Xinhua news agency reported...The statements by the companies and the environmental authorities came 11 days after the incident. Initially, officials of CNPC had denied that the Jilin Petroleum and Chemical Co plant, where the explosion occurred, had any connection to the listed PetroChina.