By Kelly Olsen
Hundreds of tonnes of highly poisonous cyanide were being stored at the warehouse devastated by two deadly explosions in the Chinese port of Tianjin, a senior military officer says.
The comments by Shi Luze, chief of the general staff of the Beijing military region, were the first official confirmation of the presence of the chemical at the hazardous goods storage facility at the centre of the blast.
Wednesday's disaster, which killed 112 people, has raised fears of toxic contamination and residents and victims' families hit out at authorities for what they said was an information blackout, as China suspended or shut down dozens of websites for spreading "rumours".
Nearly 100 people remain missing, including 85 firefighters. Eighty-eight unidentified corpses have so far been found and more than 700 people have been hospitalised.
Shi told a news conference that cyanide had been identified at two locations in the blast zone.
"The volume was about several hundreds of tonnes according to preliminary estimates," he said.
A military team of 217 chemical and nuclear experts was deployed early on, and earlier Chinese reports said 700 tonnes of sodium cyanide were at the site.
Officials have called in experts from producers of the material to help handle it.
Authorities have repeatedly sought to reassure the public, insisting that despite the presence of some pollutants at levels above normal standards, the air in Tianjin remains safe to breathe.
Chinese Premier Li Keqiang arrived in Tianjin on Sunday afternoon (local time) to direct rescue efforts, official media reported.
Pictures showed the Communist Party number two within a kilometre of the blast site, dressed in an ordinary shirt and not wearing a mask.
But the official Xinhua news agency reported late on Saturday that cyanide density in waste water had been 10.9 times the standard on the day after the explosions. It has since fallen, but was still more than twice the normal limit.
Environmental campaign group Greenpeace said on Sunday it had tested surface water for cyanide at four locations in the city and had not detected high levels of the chemical.
"These results show that local water supplies are not currently severely contaminated with cyanide," it said, but reiterated its call for comprehensive tests on the air and water and for publication of the results.
Steve Ra, an American who was evacuated by his employer to another area of Tianjin, said he was worried about the potential health effects of the blast.
"The main concern is just the air," Ra said.
Tianjin residents, relatives of the victims and online commentators have slammed local authorities for a lack of transparency, and at one point tried to storm a news conference on Saturday.
The government has moved to limit criticism of the handling of the aftermath, with a total of 50 websites shut down or suspended for "creating panic by publishing unverified information or letting users spread groundless rumours", according to the Cyberspace Administration of China.
Critical posts on social media have also been blocked, and more than 360 social media accounts have been punished.