Smoke was seen billowing from a flare as safety mechanisms kicked in at Stanlow in Ellesmere Port.
At around 2pm on Tuesday (February 4) concerned residents reported seeing thick black smoke coming from the Essar owned oil refinery site in Ellesmere Port.
Tall flames were seen flaring from a chimney as workers dealt with an onsite issue after problems with the steam supply, which saw all units being shut down.
A spokesperson for Stanlow reassured residents that no fire was taking place at the site, but that the smoke and flames were part of the safety process.
A spokesperson for Stanlow said: “Shortly before 2pm this afternoon we had an onsite issue with steam supply which resulted in all units being shut down.
“This is being done safely.
“As a result of this process flaring occurred, which will continue to diminish throughout the remainder of the day.
“We are working to restore the system safely.”