Witnesses have reported hearing a series of explosions at a industrial site in the Derbyshire town of Belper.
Pictures circulating on social media show billows of black smoke above the site.
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Business Secretary Vince Cable says the party plans to double the number of employers offering apprenticeships to young people.
A study suggests people who are obese fall into six types including heavy drinking males, young healthy females and those in poorest health.
Ed Miliband will announce the plan to crack down on exploitation which he says is driving immigration of low skilled workers and poor wages.