A dozen persons have been arrested in connection to the deadly Tianjin warehouse blast that left 145 people dead and hundreds maimed with chemical and burn injuries earlier this month.
At least 11 more are being investigated for negligence and illegally storing chemicals, state media reported.
The death toll is expected to rise with at least 28 persons still missing.
Two massive explosions ripped through a warehouse on the night of August 12 in the port city of Tianjin, less than 100 km from Beijing and considered to be part of the increasingly expanding Beijing-area.
Besides death and the widespread physical impact, the blast raised questions about the level and quality of safety controls that authorities had on such warehouses.
Investigations revealed that the warehouse stored around 700 tonnes of sodium cyanide, a toxic chemical.
For the Chinese government, usually sensitive to critical opinion, the timing of the blast could not have been worse: it occurred weeks before the high-profile military parade on September 3 to mark its victory over Japan and the end of the World War II. As many 30 heads of states are attending the military parade and Beijing - a city of 21 million - is gradually preparing for a lockdown in the run-up and on the day.
Among those arrested or being investigated are the head of Tianjin's transportation head and the top official of the city's port.
Abuse of power is included the list of accusations against those being detained or investigated.
The warehouse owner Wang Jinwen - also in the local transportation department -- held dual roles and helped bypass regulations.
"Investigations revealed, that the Tianjin Ruihai International Logistics, which owned the warehouse, handled dangerous chemicals, pass safety evaluations and obtain approvals to handle hazardous materials," the report said.