There are no reports of any injuries but residents in the immediate area are being advised to keep windows and doors closed until further notice.

Tim Longford, a farmer who lives near the site, said: “Suddenly there was a big black plume like a mushroom cloud, I've never seen anything like it.

“Fifty-foot flames spread rapidly across the whole heap and the smoke came like a curtain over the whole farm.”

A thick fog covered the surrounding four or five miles, blanketing the villages of Mickleton, Pebworth and Honeybourne.

“You can taste in on your lips,” said Mike Brain, Stratford District Councillor for Quinton. “But we've been told this morning that it's not toxic.”

But Alastair Adams, who is the Wychavon District Councillor for Honeybourne and Pebworth, asked how they could be so sure.

Having witnessed the fire last night, which he said looked like “a nuclear bomb”, he woke up with a dry mouth and a metallic taste at the back of his throat.

“It was just horrendous, absolutely horrible,” he said.

The second large fire at the plant in the past month, residents think Sims have been stockpiling too much metal and working out of hours.

The site is reportedly only allowed 20,000 tonnes of material, but last month there was in excess of 100,000 tonnes on the site,

This has been reduced to around 60,000 tonnes, and management have previously said it is their plan to clear the site by July.

Mr Longford also pointed out that Sims only have a license to operate until 8pm and last night's fire started at 8.45pm.

Sims are also currently investigating a case of fraud at their Long Marston site, and have been forced to write off £52 million.

Mr Adams said there was definitely something “fishy” going on.

This morning, although the fire is now under control, the metal is still alight.

Station Commander Gary Jay from Hereford and Worcester Fire Service said: “This is a deep-seated fire and we anticipate that it will be on-going for some time yet.

“We are monitoring the weather and wind patterns, and liaising closely with police, the Environment Agency, local health and on site staff to determine a plan as we move forward.”