The cause of a major fire that created ‘hazardous smoke’ has been revealed.

Firefighters were called to a recycling centre in Millbank Street on Wednesday night.

A large plume of ‘hazardous’ smoke billowed into the air, travelling across the River Itchen towards Bitterne as the fire was tackled.

Fire crews were on the scene – belonging to metal recycling group EMR - for more than five hours.

The cause of a major fire at a scrapyard in Northam, Southampton has been revealed (Image: Newsquest) Now, the cause of the ferocious blaze has been revealed.

A spokesperson from EMR said: “The suspected cause of the fire was a concealed lithium-ion battery - a prohibited item that EMR works very diligently to keep out of the metal recycling stream.

“Despite EMR’s industry-leading quality assurance protocols, our recycling facilities encounter recyclable metals containing these highly dangerous lithium-ion batteries.

“We are committed to working with our customers to implement proactive measures to reduce the presence and impact of these dangerous materials.”

The facility is operational again following the fire and there were no casualties, the spokesperson confirmed.

They added: “We take incidents like this very seriously and we will review the circumstances and take any learnings we can to continue improving our procedures. “

Seven fire engines attended in total from St Mary's, Hightown, Redbridge Hill, Botley and Romsey.

Two aerial ladders were used and the environmental protection unit were also called to monitor the flow of the water leading away from the area.