LONDON — A fire broke out at a Shell-owned chemical plant in northwestern England on Wednesday but operations at Essar Oil UK's Stanlow refinery on the same site were unaffected, Essar said.

The Shell Higher Olefins Plant (SHOP) is separated from the refinery by a road and rail tracks. Essar operates the chemical plant as well as the refinery.

"Earlier this afternoon, a fire occurred at the SHOP chemical plant," an Essar spokesman said.

"Refinery operations at Stanlow remain unaffected," the spokesman said, adding all staff were safe and accounted for.

At Stanlow, Shell uses ethylene to manufacture polymer, lubricant and detergent intermediates, plasticizers and detergent alcohols, according to its website. Shell was not immediately available for comment.

Earlier on Wednesday, fire engines from five different locations were sent to the 200,000 barrel per day oil refinery.

"There was a report of a large plume of black smoke. We have several pumps at the scene," a spokeswoman for the Cheshire fire service said. In a statement, the service said engines from five locations were on the scene.

Essar Oil UK, owned by the Indian billionaire Ruia brothers' Essar Group, bought the refinery near Ellesmere Port from Shell in 2011. Around 900 people work at the refinery, according to its website.

"The site produces a range of oil products including about one sixth of Britain’s transport fuels annually - about 4.4 billion liters of diesel, 3 billion liters of petrol and 2 billion liters of jet fuel," Essar Oil UK's website said.

Last September, Essar Oil UK said it expected a $250-million upgrade of the refinery. Recent expansion work was finished in March. — Reuters