Natural Resources Wales are investigating a potential pollution incident in the River Cain after a large pile of debris was set alight in Llanfyllin on Tuesday, June 5.

Residents say cloud of toxic black smoke hung over parts of the town after a 10ft pile of rubbish including tyres and plastics was set alight.

Firefighters from Llanfyllin were called to an incident on open land near the river at 11.40 after nearby residents raised the alarm, spending several hours extinguishing the blaze.

An environmental unit from Newtown was also called to the scene to assist with the clean-up operation and prevent water and waste from the fire running in to the river.

"The fire contained old tyres and plastics and was causing significant air pollution with a risk of water pollution to the nearby River Cain," said a spokesperson for the fire service.

"We had to contain the water to stop pollution flowing into the watercourses. There are houses nearby and the smoke was pretty intense."

Neighbours say they were alerted by black smoke and explosions as aerosols in the debris pile exploded.

"Neighbours were very concerned as there was a big bang from one of the aerosols exploding, and with it being so close to a residential area where there are lots of children," said resident Cordelia Weedon.

"It took most of the day and had to get a JCB to move the rubbish and make sure it was completely out. They had to call in a special unit from Newtown to check none of the water went into the river.

"This is not the first time it’s happened, we'd like to see this anti-social behaviour stopped," she added.

Natural Resources Wales say they are looking in to the incident with a view to taking what it describes as appropriate action.

Liz Park, Environment Officer, Natural Resources Wales said, "We work to keep people and wildlife safe from environmental risks such as pollution.

"Our local officers attended the site and worked with Mid and West Wales Fire and Rescue Service to stop fire water run-off polluting the River Cain.

"We will now be investigating the cause of this incident and will take the appropriate action in accordance with our enforcement and prosecution policy."