Rescuers are cleaning hundreds of tonnes of highly-toxic cyanide remaining in north China's Tianjin city following warehouse blasts that killed at least 112 people on Wednesday night.

Initial estimates put the amount of cyanide at the site at hundreds of tonnes, most of which was unaffected, said Shi Luze, chief of staff of the Beijing Military Area Command at a press conference on Sunday.

Lu said rescuers were using hydrogen peroxide to neutralize the toxins and building cofferdams to enclose the damaged barrels, while trucking away those intact.

Only safe levels of harmful gas were detected near the blast site, Lu added.

A total of 112 bodies have been found, and 95 people remained missing, including 85 firefighters, after two explosions took place in a warehouse for hazardous chemicals following a fire, sending a mushroom cloud into the sky and shattering glasses several kilometers away.

The missing firefighters included 13 in active service, and 72 working for the Tianjin Port Group Co., said Gong Jiansheng, vice head of the city's publicity department.

Only 24 victims have been identified so far, he added.

A total of 722 people remained in hospital, including 58 in critical or serious conditions, the rescue headquarters said on Saturday night.

Bao Jingling, chief engineer of the city's bureau of environmental protection, said among the 17 monitoring sites outside the alert zone, two reported readings of hydrogen cyanide slightly above the normal standards which would not pose threat to health.

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