A spokesman for West Midlands Fire Service has said the fire at the Smurfit Kappa plant in Birmingham is in "a very large outside storage area, containing cardboard bales".
The site in Mount Street, in the Nechells area of the city, is a recycled packaging mill.
According to its website, Smurfit Kappa is one of the leading producers of paper-based packaging in the world with more than 41,000 employees in 32 countries.
More top news
A sigh of relief across Westminster and a crushing sense of disappointment for 45% of Scotland, but Yes campaign could not have done more.
ITV Border Political Editor Peter MacMahon says we've just seen a emotional former SNP MSP appearing to concede that the Yes side has lost.
ITV Border Political Editor Peter MacMahon says it's far too early to call this referendum.