Caia Park Environmental Group has carried out work to improve land around the Communities First Centre near the river Gwenfro and over half-term held a two-day environmental activity event for 21 children, warning them of the consequences of lighting bonfires.

Yet on bonfire night two fires at least 12ft across were lit near the river – one outside the centre and one on the opposite river bank.

Dorothy Mitchell, chairman of Caia Park Environmental Group, said: "Again it is a shame to see that bonfires built on this area have caused such unnecessary damage to the environment. One of these bonfires is on a site that is used for community environmental activities close to the river and trees and it is where children play.

"It's criminal that these bonfires were made when there was a community-organised bonfire which was safer and within five minutes walking distance."

Dorothy said it will take six months for the ground to return to its natural state and she is worried about the toxins that were released from the bonfires as well as the visual pollution that the mess that is left has caused.

"We've just done a two-day environmental action event over half-term, looking at pollution and warning against fly tipping," she added.

"With bonfire night coming up we told people that the things they collect for the bonfire could be nasty toxic stuff and we were talking to children telling them they could be fined because building a bonfire is flytipping.

"The council has now been left to clear up the mess and the fire brigade had to put them out, causing unnecessary expense.

"Perhaps next year people will go to a community event rather than cause an issue like this."