The Environment Agency has described a cyanide spill into a West Midlands canal as “unacceptable” and promised robust action if any wrongdoing is found to have occurred. A major incident was declared after the spill of sodium cyanide into a canal in Walsall on Monday. The public have been advised to avoid about 12 miles of canals and towpaths in the area and on Thursday a UK waterways boss described the situation as “distressing” and “infuriating”. The Environment Agency said it was investigating a metal finishing company, Anochrome Ltd, after the spill. Anochrome said it had immediately notified the agency and Severn Trent Water after the incident and its senior management team remained on site working to minimise and contain the spill. Experts said ingestion of water with a sufficiently high amount of sodium cyanide could result in symptoms of nausea, weakness, aches and loss of consciousness. Dozens of dead fish have been spotted in the canal and there are concerns about the wider effect on wildlife. Richard Parry, the chief executive of the Canal & River Trust, told BBC Radio 4’s Today programme: “It’s very serious, it’s very distressing and it is infuriating. Canals provide such benefits for people and for nature … they run through so many communities and to have a chemical of this toxicity released into the canal is extremely distressing.” He said the spillage may have passed through a surface water drain. “That needs to be confirmed by the investigation,” he said. “How on earth a chemical of this toxicity would come to go into a surface water drain is baffling and infuriating.” Parry said the focus was on containment and then recovery. Overnight the trust put in some dams to help prevent spread. “We’re hopeful, once further testing is done, once we’ve spoken to the other agencies involved, that it may be possible at some point to reduce the affected area,” Parry said. A spokesperson for the Environment Agency said: “We are working closely with Walsall council and the UK Health Security Agency to respond to the serious chemical spill incident in Walsall and to assess the impact on the environment. We are now investigating the company that is believed to have caused this incident. “Pollution of this kind is unacceptable and the impact on wildlife and the environment can be severe. We will take robust enforcement action if non-compliance is uncovered. We have established a sampling and testing programme and urge the public to follow safety advice given by the local council.” A spokesperson for the Department for Environment, Food and Rural Affairs said ministers were closely monitoring the situation, adding: “Toxic pollution of this kind is disgraceful.” Walsall council said it had been notified of a spillage in the canal at Pleck, which stretches for more than a mile from Spinks Bridge to Birchills Street Bridge, on Monday. A major incident was declared the following day. It has posted a map showing the canals the public should stay away from. It includes waterways from Walsall lock flight to lock flights at Rushall, Ryders Green and Perry Barr. Anyone exposed to the canal water in the area who is feeling unwell is advised to seek health advice by calling 111 or, in an emergency, 999. Anochrome describes itself as “a quality conscious and environmentally aware organisation” on its website. In a statement the company confirmed that a chemical incident occurred in Walsall in the early hours of Monday. “Regrettably, as a result, some of the released chemicals entered a canal in Walsall.” It added: “The safety of our community and the environment is our top priority. We are focused on limiting the impact of this incident and will provide further updates as they become available.”