People in Tianjin whose homes were damaged by the huge explosions on August 12 have staged protests to demand compensation from the Chinese government.

Scores gathered outside the Mayfair Hotel, where officials have been giving news conferences.

Residents say the chemical storage warehouses which blew up had been built illegally close to their homes.

The explosions focused on a warehouse which was storing sodium cyanide.

An investigation into the cause of the explosions is under way.

The warehouse was storing hundreds of tonnes of sodium cyanide, far more than legally allowed. It was also within 1,640ft of homes, flouting laws which state a 1km minimum distance.

Local media had earlier reported that there were at least three residential complexes within one mile of the warehouse, which belonged to Ruihai International Logistics.

In the latest in a number of small protests, the people gathered at the Mayfair Hotel on August 17 said they wanted compensation for their damaged homes, and would refuse to return to them even if they were ruled safe.

In an open letter to the authorities, the residents said their groundwater could have been contaminated, and that logistics companies and chemical “dumping grounds” remained close to residential complexes.

“Our neighbors lost their lives there. Their screams can never be erased for a long time. How can we live in that ‘execution ground’ with any peace of mind?” the letter states.

Sodium cyanide is white crystalline or granular powder which can be rapidly fatal if inhaled or ingested, as it interferes with the body’s ability to use oxygen.

It is mostly used in chemical manufacturing, for fumigation and in the mining industry to extract gold and silver.

It is soluble in water, and absorbs water from air. Its dust is also easy to inhale. When dissolved or burned, it releases the highly poisonous gas hydrogen cyanide.

Public demonstrations remain rare in China, but authorities have allowed some criticism on the highly-publicized Tianjin incident, with even state media taking issue with local authorities’ handling of the matter.

Many of the rules designed to keep people safe in Tianjin were bent, broken or ignored.

There have also been real questions about the leadership and training of the firefighters who arrived first on the scene on August 12 – all but a handful are missing or dead.

Tianjin Deputy Mayor He Shushan promised: “Once we find any actions that have violated the regulations and laws, we will resolutely punish them and give answers to the victims and people affected.”

The protests come amid continuing uncertainty about the wider environmental impact of the explosion, although state media have sought to tamp down rumors of widespread contamination.

Authorities are still cleaning up the site and putting out the fire at one last active burning point.

Officials said on August 17 that three waste water discharge monitoring stations within the 3km-radius evacuated area around the blast zone found excessive levels of cyanide, with one station recording a level 27.4 times the normal limit, reported People’s Daily.

However, authorities have stressed that the area is sealed off and hazardous material was contained at the site, and that all the sodium cyanide would be collected and neutralized by the day’s end.

They also said only one air quality monitoring station had detected a minimally higher level of hydrogen cyanide.