More Than 50 Killed in China Pipeline Blasts BEIJING—Explosions at a pipeline that left dozens dead and upended cars and sidewalks in a busy Chinese port city have renewed focus on industrial facilities in densely populated areas—an issue of rising importance as Beijing pushes an ambitious urbanization plan. Regulators and the pipeline's operator, China's largest refining company, began exchanging blame on Monday over the Friday incident in the eastern city of Qingdao, which drew widespread attention across the country and prompted a visit by PresidentXi Jinping to a local hospital to meet with victims. Authorities on Monday raised the death toll to 55, with 136 injured and nine still missing. Chinese authorities said Monday that the blasts exposed problems caused by human error and that the accident was a "very serious dereliction of duty," China's official Xinhua news agency said, citing Yang Dongliang, director of the State Administration of Work Safety. Mr. Yang said the problems included how the pipeline and the city's sewage and underground cable systems had become intertwined. But he also cited "negligence of duty of pipeline supervision and unprofessional handling of oil leakage before the blasts." A representative for China Petrochemical Corp., known as Sinopec Group, said the government investigation was continuing and the cause of the blast had yet to be determined. But the company defended its conduct, saying authorities in another city with oversight over the pipeline didn't sign off on an overhaul. The representative also said the area around the pipeline wasn't as populated when it was completed 27 years ago. "The city began to expand and people gathered," the Sinopec representative said. "Buildings and other utility pipelines were built near our oil pipelines." Qingdao's rapid urbanization and fast-paced industrialization illustrates the challenges that China's leaders face in planning for economic growth. Qingdao's population jumped to 8.5 million in 2010 from 6.3 million in 1986. In 2011, Qingdao completed a 17-mile bridge across Jiaozhou Bay to alleviate traffic that choked a highway that curved around the bay. That structure connects its downtown with the district of Huangdao, where Friday's explosions occurred, and accelerated Huangdao's development. "I wonder why so many factories and companies have been built in the area, and why people are being directly exposed to pollution and explosions," said a Huangdao resident calling herself Xiao Rou on her microblog. "Why doesn't the government take measures? …I hope the government can give us a safe home." Sinopec and other companies have previously faced protests in several cities over efforts to build or expand industrial facilities near densely populated areas. Last year, residents in the eastern Chinese city of Ningbo forced officials to suspend the planned $8.9 billion expansion of a petrochemical facility run by Sinopec, which began operating in the area in 1975. Part of the new facility was supposed to produce the industrial chemical paraxylene, which residents feared could be damaging to their health and the environment. Such incidents come as China pushes to move more rural residents into the cities as a way to spur greater consumption to help rebalance its economy. A blueprint for reform by China's leaders released this month called for greater access to urban services for rural migrants and greater land rights for rural residents, which could give them added impetus to sell and move. In 2009, China's State Council, or cabinet, began deliberating precautions on construction around pipelines. "Rapid urbanization had resulted in the reckless construction of buildings and roads within buffer areas for the pipelines in recent years, making their protection increasingly difficult," Xinhua said at the time. The explosions on Friday occurredas workers tried to clear a spill from a leak that began in the early hours. Authorities said there were explosions in two areas. The pipeline, built in 1986, carries crude oil from Huangdao to processing facilities in the city of Weifang about 170 kilometers, or about 100 miles,away. Sinopec said it submitted plans to Weifang's Ministry of Environmental Protection to overhaul sections of the pipeline in 2011 and 2012, but the plans were rejected. Sinopec warned Weifang that nearby roads, houses and buildings could create potential hazards, the representative added. "If there were any incidents, we wouldn't be able to repair our pipelines conveniently and immediately," the Sinopec representative said. However, "the [Weifang] government didn't agree with our plans to repair the aging pipeline, so we couldn't do it." Representatives from Weifang and its environmental protection branch didn't reply to requests to comment. Although the pipeline crosses through several regions and ends in Qingdao, Sinopec said it was required by Chinese law to seek permission from local authorities in Weifang, where the company's pipeline subsidiary is registered.A Huangdao municipal government spokeswoman referred questions to Sinopec. Sinopec's pipeline hasn't been immune to past problems. Oil spills and fires resulted from two 2010 incidents, according to company statements, though no casualties were reported. Sinopec blamed the buildup of trash on a section of the pipeline and illegal construction near it. Xinhua quoted the Chinese president as saying on Sunday that safety must be improved in the pipeline industry, and he called for stronger inspections and punishments for violations. Mr. Xi added that pipeline operators should carry out surprise inspections and enforce a "zero-tolerance" policy for violations. Although China has had other pipeline explosions in the past, Friday's blasts were the deadliest in recent memory. In 2010, a series of oil-pipeline explosions rocked the shipping and tourism city of Dalian, sparking fires that blazed for 15 hours. However, there were no casualties. —Olivia Geng and Grace Zhu contributed to this article.