The Ministry of Transport said that an explosion of oil pipelines in Dalian was caused by improper operations carried out by port workers, contradicting an initial statement which blamed the crew of a tanker. The explosion spilled an estimated 1,500 tons of crude into some 430 square kilometers of seawater. A PetroChina executive expected the port to be closed for at least a week. Dalian sent 800 vessels to clean up the spill and the number is expected to increase to 1,000. Authorities built 9,000 meters of floating fences to prevent oil spreading, and threw 3.7 tons of felt and 22 tons of neutralizing chemicals onto the water’s surface to help absorb the oil. Dalian officials said the clean-up would take about a week, but an official from the State Oceanic Administration said it would take much longer. Professor Yan Jienian of the China University of Petroleum expected the clean-up could take three to five months. A total of 44 vessels scheduled to anchor at the Xingang port were redirected to a nearby port. The livelihoods of thousands of fishermen in Dalian have been threatened by the oil spill and few tourists have visited Dalian’s beaches since the explosion. Chinese authorities are trying to prevent the oil spill from reaching international waters. China National Petroleum Corp (CNPC) announced that a key pipeline had resumed operations after the  explosion caused the country’s largest reported oil spill. The pipeline is now pumping 45,000 tons of crude oil a day from part of China’s strategic oil reserves. The State Administration of Work Safety said improper desulfurizer injections performed by Shanghai-based Q.PRO Inspection and Technical Service Co caused the July 16 explosion.