Rescuers clean up containers at the core area of the warehouse explosion in north China's Tianjin Municipality which occurred on Aug 12, 2015. [Photo/Xinhua]

The Tianjin company and the government departments are both blamed for the accident.

"The company seriously breached rules ... and illegally stored the chemicals," said Li Wanchun, head of the team's management group. "Its operation ... had had potential safety hazards for a long time."

As a supervisor of the port, the Tianjin Transportation Commission did not conduct safety checks in line with the law and had lapses in its inspections, Li said.

In addition, many officials involved are also suspected of power abuse and bribery, he said.

"We found some people in the city's Planning Bureau and Land Department allegedly helped the company illegally get the planning permits and made fake certificates in safety and environmental assessments," he said.