Beijing: Chinese police have arrested 12 people over giant explosions that killed 139 people and devastated a swathe of a Chinese port city, state media said Thursday as prosecutors probe 11 officials for neglecting their duties.

The official Xinhua news agency said the dozen formally held include the chairman and senior managers of the firm whose chemical storage facility exploded in the northern city of Tianjin two weeks ago, in the country's highest-profile industrial accident in years.

Separately, the Supreme People's Procuratorate said on its website that prosecutors in the city were also probing 11 officials for ‘abuse of power’ and ‘dereliction of duty’ over the blasts, which also injured hundreds of people.

In China, formal arrest normally comes after some time in police detention and sees the case handed to prosecutors, with trial and conviction almost guaranteed.

The 12 arrested include owners of Rui Hai International Logistics who were shown on state television last week, when they were already being held by police, ‘confessing’ to using government connections to obtain safety permits.

More than 500 people remain in hospital after the huge explosions, which left a trail of mangled buildings and burnt out cars in their wake.

The incident sparked widespread outrage over alleged safety violations by the firm and possible official collusion, and fears of pollutants contaminating the air and water of Tianjin, home to about 15 million people.

Communist authorities and state-run media have sought to pin blame for the disaster on local individuals and officials, rather than systemic factors.

Prosecutors said the officials they were investigating came from several government departments including transportation management, customs and work safety, and the president of a state-owned port company in Tianjin.

Industrial accidents are common in China, with corruption thought to be a key factor behind lax enforcement of safety regulations.

The head of China's work safety watchdog -- a former vice-mayor of Tianjin -- has been sacked after a suspected corruption investigation, state media said Wednesday.