Chinese state media appeared to convict executives of a company whose chemical warehouse exploded last 114 people of slipshod practices at least, saying they used connections to obtain fire safety and environmental approvals.

Public anger against the government has surged in the northeastern port of Tianjin among residents of apartments near the blasts who believed authorities neglected to properly police the firm, Tianjin Dongjiang Port Ruihai International Logistics.

"My connections are with police and fire. When we needed a fire inspection, I went to meet with officials at the Tianjin port fire squad," Dong Shexuan, 34, deputy head of the company, told the official Xinhua state news agency while he and other executives were in police custody.

"I gave them ... the files and soon they gave me the appraisal and took care of it."

Company executives interviewed by Xinhua could not be reached for comment. Chinese state media often airs confessions of those detained in high-profile criminal cases before they are tried in court, a practice that rule of law advocates say violates the rights of the accused to due process.

Xinhua said Dong did not mention any instances of bribery.

The explosions in the world's 10th-busiest port forced the evacuation of thousands of people after toxic chemicals were detected in the air. At least 10 people from the company have been detained.

China has struggled in recent years with accidents ranging from mining disasters to factory fires, and President Xi Jinping has vowed that authorities should learn the lessons paid for with blood.

Apartment buildings and a railway station were closer to the warehouse than allowed by Chinese regulations dealing with the storage of dangerous materials, state media has reported.

Hundreds of people who lived near the blast site have demanded that the government arrange compensation or buy back their damaged or destroyed property.

Dong said company officials shopped around for approvals with different safety evaluation firms until they got the result they desired. The first such firm said the warehouse was too close to apartment buildings, he said.

China said it was investigating the head of its work safety regulator, who for years allowed companies to operate without a license for dangerous chemicals.

The People's Daily, the ruling Communist Party's official newspaper, said that Ruihai had operated without a license to work with dangerous chemicals because of an administrative loophole, though Reuters could not verify that report.

Tianjin mayor Huang Xingguo told reporters at a briefing that all chemical companies would be required to relocate 25 km (15 miles) from the port central Binhai district and that there would be "zero-tolerance" for violations.