China said on Tuesday it is investigating the head of its work safety regulator who for years allowed companies to operate without a license for dangerous chemicals, days after blasts in a port warehouse storing such material killed 114 people.

Yang Dongliang, head of the State Administration of Work Safety, is “currently undergoing investigation” for suspected violations of party discipline and the law, China’s anti-graft watchdog said in a statement on its website.

The agency, the Central Commission for Discipline Inspection, did not say that Yang’s behavior was connected to the explosions in the port of Tianjin but the company that operated the chemical warehouse that blew up did not have a license to work with such dangerous materials for more than a year.

Investigators have not determined the cause of the blasts but the disaster has deepened public concern about safety regulations.

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

The People’s Daily, the ruling Communist Party’s official newspaper, said last week warehouse owner Tianjin Dongjiang Port Ruihai International Logistics had operated without a license to work with dangerous chemicals because of an administrative loophole.

Reuters could not verify that report but the company did not have any form of certification, including a license to handle dangerous goods, between October 2014 and June 2015, according to its records on the State Administration for Industry and Commerce (SAIC) website.

The agency is one of many government departments that regulate companies that operate with dangerous materials.

The Xinhua news agency said the company worked with hazardous chemicals throughout that period, citing an unidentified company official.