Masked rescuers clear the blast zone in Tianjin where an explosion at a warehouse last week killed more than 116 people, Aug 19, 2015. [Photo/Xinhua]

The government has inspected 275 companies dealing with dangerous chemicals in Tianjin Binhai New Area and closed 70 that have safety problems following last week's deadly blast, said a senior official on Friday.

Zhang Yong, head of Tianjin Binhai New Area, said at a press conference that the inspection, jointly conducted by several departments, is ongoing at the moment and those around the residential compounds and schools will have top priority.

As of Friday, the blasts on Wednesday night that rocked a warehouse storing hazardous chemicals have claimed 116 lives with their identities all confirmed, including 65 firefighters and seven policemen, and left 60 missing.

More than 200 tons of toxic sodium cyanide scattered in the core zone have been collected but those left in the containers remain to be collected, said Wang Hongjiang, deputy mayor of Tianjin who is in charge of the cleanup work.

"But there are about 40 kinds of chemicals stored in the warehouse. The situation is very complicated. We have a comprehensive plan but no deadline can be given at the moment," Wang said.

Wang said they have an emergency plan to deal with storms and strong wind, without excluding the possibility of evacuation of the team from the core area.

Wang assured residents that the tap water network is not contaminated as it has been blocked and is not connected to the outside area.

According to Deng Xiaowen, head of the Tianjin Environment Monitoring Center, eight of 26 water monitoring stations in the core blast zone have detected concentrations of highly toxic cyanide compounds exceeding the national standard, with the highest being 356 times the standard.