The Chinese firm whose warehouse in Tianjin exploded last week killing at least 114 people did not have a licence to handle hazardous chemicals until two months ago, Xinhua news agency says.
It also said that for eight months before June, Tianjin International Ruihai Logistics handled hazardous chemicals without the right documents.
Nearly 700 people were injured in Wednesday’s devastating blasts.
Ceremonies in the port city honoured the dead on Tuesday.
Cargo ships blared their horns and people gathered in silence to mark the day.
Residents have been staging protests demanding compensation for property damage from the government.
Thousands of people had to evacuate their homes after toxic chemicals were detected in the air following the blasts at the world’s 10th-busiest port.
Some 17,000 homes were damaged by the explosions and their shockwaves.
The warehouse was storing hundreds of tonnes of sodium cyanide, far more than legally allowed, it has emerged.
It was was also within 500m (1,640ft) of homes, in violation of laws that require a 1km minimum distance.
On Tuesday, Xinhua quoted an unidentified executive from the company as saying: “The company has handled hazardous chemicals during a period without a licence.”
The agency said documents showed the company was approved to handle hazardous chemicals between April and October last year.
Tianjin – the toll
- Officials now say 114 people died in the explosions
- Still missing: 70, mostly firefighters
- Nearly 700 are still in hospital
- At least 6,000 people have been displaced, state media report
- Some 17,000 homes damaged by the blasts and their shockwaves
Ruihai obtained a port operation licence two months ago which again allowed it to work with toxic chemicals, Xinhua said.
Ten people, including Ruihai head Yu Xuewei and deputy head Dong Shexuan, were detained last Thursday, state media reported.
China’s top prosecutor is reported to be investigating all involved officials for dereliction of duty and other crimes.
Doubts have also been cast on a consultation process Ruihai claims it had with residents, in which most respondents were said to have raised no objection to the company operating.
But residents told Xinhua they did not respond to any questionnaires.
Meanwhile, heavy rain has hampered recovery efforts.
Experts expressed concern that rain could spread some of the vast quantities of hazardous material at the site or set off chemical reactions sparking further explosions
What is sodium cyanide?
The chemical sodium cyanide is white crystalline or granular powder which can be rapidly fatal if inhaled or ingested, as it interferes with the body’s ability to use oxygen.
It is mostly used in chemical manufacturing, for fumigation and in the mining industry to extract gold and silver.
It is soluble in water, and absorbs water from air. Its dust is also easy to inhale. When dissolved or burned, it releases the highly poisonous gas hydrogen cyanide.