Journalists prepare to take pictures and conduct interviews near the scene of the blasts at Tianjin Port on Monday. Zhu Xingxin / China Daily

About 3,000 tons of highly hazardous chemicals were stored at the warehouse in Tianjin when it was hit by explosions last week, said an official on Monday.

Among the detected 40 kinds of poisonous chemicals, there are 700-ton sodium cyanide, 800-ton ammonium nitrate and 500-ton potassium nitrate, according to Niu Yueguang, deputy director of the Ministry of Public Security.

Seven hundred metric tons of sodium cyanide found on the site of deadly blasts in Tianjin has been confirmed to have been produced by a company in neighboring Hebei province.

"We are striving to deal with the substance," said Zhi Qunshen, CEO of the Chengxin Co in Heibei.

If there is any leakage of sodium cyanide at the blast site, hydrogen peroxide will be used so that the toxins could be quickly broken down into less toxic chemicals, said Shi Luze, chief of staff of the People's Liberation Army's Beijing Military Area Command.

Stored in cans weighing 50 kilograms each, the chemicals were all supposed to be exported to "customers from more than 10 countries, mainly local mining industries", Wang Jianfang, director of the office of Chengxin Co, told Beijing News, adding that the company has all the documents required for export.

Though a fatal chemical if inhaled, sodium cyanide is commonly used in the mining industry to extract gold from ore - a gold leaching agent that "could largely lower the cost of the extraction process", Chen Jinghe, CEO of Zijin Mining, told China Business News, while admitting that there is a great risk of environmental damage if transportation of the chemical is not strictly regulated.