Residents in County Durham are being warned to only employ reputable traders after repair work carried out on one person’s home was found to be potentially deadly.

Trading standards officers from Durham County Council are investigating the incident, in which a chimney was left blocked up by a trader touting for work in the south east of the county.

The trader told the householder that the chimney needed repairing and that people from neighbouring properties had complained about a brick falling from it.

But after the work had been completed it was discovered that the chimney had been left completely blocked with no ventilation.

The consequences, had the householder used their gas fire, would have been a build up of carbon monoxide inside the property which could have proved fatal.

The problems came to light when the householder contacted trading standards after being left dissatisfied with the standard of the work.

The incident is under investigation and Durham County Council is warning householders to be wary of employing tradesmen who cold call residents and who they have no prior knowledge of.

Joanne Waller, head of environment, health and consumer protection at Durham County Council, said: “Durham County Council operates a Registered Trader Scheme, which is a list of vetted traders who are committed to honest and fair trading.

“It gives the consumer peace of mind that a trader on the scheme has satisfied membership criteria, including a check on criminal convictions, a police check for employees and sub-contractors, county court judgement checks and references from previous customers.

“We urge people to carry out necessary checks on all tradesmen prior to agreeing to work being carried out on their home.

“We have seen many residents pay extortionate amounts of money for work on their property following contact from unscrupulous traders and this latest incident has also highlighted that in some cases the work carried out can put lives at risk.”

People can get further information about the Registered Trader Scheme by contacting Durham County Council on 03000 261 016 or by visiting www.durham.gov.uk/registeredtraders