Media playback is unsupported on your device Media caption An eyewitness captures the fear of those watching the explosions

Eighty-five people are now known to have been killed in giant explosions in the Chinese port of Tianjin on Wednesday, local officials say.

At least 21 firefighters are among the dead, with another 721 people injured after the blasts at a warehouse storing hazardous materials.

The operators of the Tianjin site have been accused of "clearly violating" safety rules.

China has ordered a nationwide check on dangerous chemicals and explosives.

China's cabinet also ordered officials to "crack down unwaveringly on illegal activities to ensure safety".

Twenty-five of the injured are in critical condition and 33 are serious.

Some fires are still smouldering and chemical experts are testing for toxic gases.

The cause of the blast is still being investigated.

Cyanide fears

Officials have only confirmed that calcium carbide, potassium nitrate and sodium nitrate were at the warehouse.

But there were reports in the People's Daily that 700 tonnes of sodium cyanide were at the Tianjin site. Ammonium nitrate may also have been present.

Chinese officials, though, have admitted there are discrepancies between accounts from the company and from customs, and that damage to company offices had made it hard to identify the chemicals.

More than 200 chemical and biological experts from the military are on site but officials insist that the air and water quality levels in Tianjin are safe.

People's Daily said the Tianjin facility, operated by Ruihai Logistics, had "clearly violated" safety rules that say dangerous materials must be stored at least 1km (0.6 mile) away from public buildings and main roads.

State media said the manager of the Ruihai Logistics site had been detained.

Media playback is unsupported on your device Media caption Dashboard camera captures China blast shockwave

Media playback is unsupported on your device Media caption Aerial views of the site of the explosion in Tianjin

Water factor?

Fire officials have defended the actions of the team who responded to the initial report of a fire on Wednesday night, amid suggestions that using water on some of the chemicals could have led to the blasts.

Calcium carbide reacts with water to create the highly explosive acetylene.

Fire department official Lei Jinde said: "We knew there was calcium carbide inside but we didn't know whether it had already exploded. At that point no-one knew, it wasn't that the firefighters were stupid."

They would not have sprayed water on calcium carbide, he said, although he admitted it was a large warehouse and the team could not be sure where that substance was.

Chemical experts suggest an acetylene blast could then have detonated ammonium nitrate causing a much larger blast.

There were two explosions. The first was equivalent to about three tons of TNT, the second - some 30 seconds later - was equivalent to 21 tons.

Image copyright Reuters Image caption Paramilitary police in gas masks have been collecting samples

Image copyright Reuters Image caption Fires are still smouldering at the site

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