Chinese officials have blamed the chairman of a car-parts factory in eastern China and local regulators for safety breaches that led to the deadliest industrial accident in a year, the official news agency Xinhua reports.
The blast at the Kunshan Zhongrong Metal Products Co Ltd factory in the city of Kunshan on Saturday killed at least 75 people and injured 185.
A preliminary investigation cited on Monday suggested the blast was caused by a flame lit in a dust-filled room, local government officials said.
Dust can be highly explosive when it is suspended in air in the right concentrations.
Kunshan Zhongrong, which polishes aluminium wheels for car manufacturers including General Motors, failed to properly store dangerous goods, did not have appropriate ventilation or dust removal systems and had a substandard electrical system, according to the government investigation cited by Xinhua.
The factory also ignored prior warnings about dust, did not have appropriate fire safety equipment and did not provide safety training for workers, according to the report.
A senior official in charge of China's work safety administration called the situation a "very serious dereliction of duty", Xinhua reported.
Neither Kunshan officials nor executives from Kunshan Zhongrong could be reached for comment.
'No direct dealings'
General Motors said on Sunday that it had asked its main Chinese supplier to find an alternative source of components after the explosion.
The Detroit car manufacturer issued a statement saying it bought components from a company called "Dicastal" - which Zhongrong works with.
GM went onto say it had no direct dealings with Zhongrong, which it described as a "Tier-2" supplier.
A GM spokeswoman in Shanghai said she had no information on whether GM conducts safety inspections of production facilities run by lower-tier suppliers with which they do not do business with directly.
Xinhua said previously that two company representatives had been taken into police custody and that President Xi Jinping had demanded a full inquiry into what happened and punishment for those responsible.
It said on Monday that the State Council had approved a special task force to investigate the accident and would soon
carry out nation-wide inspections on plants and their dust control measures.
It also said that authorities would draw up comprehensive regulations and standards on dust control at factories.