Concerns have been raised about flaring from the Stanlow oil refinery which generated a plume of thick black smoke visible from miles around.

Essar, who operate the site at Ellesmere Port, have apologised for “any inconvenience” and say equipment failure activated a safety system which caused excess flaring which has now been resolved.

However, there was confusion after Cheshire Fire and Rescue Service initially claimed it was given a different version of events, tweeting: “Reported smoke in Ellesmere Port has been confirmed by Essar as part of their fire training.”

Essar says it “did not supply that information”.

A later tweet from the fire service said the cause was due to an ‘equipment trip which is now back online’, adding they were not required to attend.

Essar can’t explain the reason behind the differing versions except that it must have been a “misunderstanding”.

Marilyn Chew from Saughall was so concerned about this and a previous incident that she called The Chronicle and the Environment Agency.

She said: “I would not normally phone a local newspaper up. I’m not an alarmist but this is the second time I have had to phone up the agencies – first I rang environmental health a couple of months ago and I have just spoken to the Environment Agency.”

Mrs Chew, who wants to raise public awareness about the situation, added: “It goes on for hour after hour after hour. It’s got to be a hazard to the environment.”

Essar spokesman Ian Cotton said: “I understand it was not a training exercise. There was a ‘trip’ of a piece of equipment, the system worked as it was meant to do and you get visible flaring. That equipment is now back online. We apologise for any inconvenience caused.”

Back in February, tall flames and thick black smoke were seen billowing from the Essar flare when safety mechanisms again kicked in. Workers had to deal with an onsite issue after problems with the steam supply, which saw all units being shut down.

But Mr Cotton insisted: “We have a good safety record.”

He was “not sure” why Cheshire Fire and Rescue Service had initially offered a different reason for the latest incident but stressed there was “a very good working relationship” between the two organisations.