Around 10,000 tonnes of recycled cardboard bales are on fire at the Smurfit Kappa paper mill in Birmingham, West Midlands Fire Service has said.
The service said crews and agencies are continuing to battle high winds but are "working extremely hard" to bring the blaze under control.
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.
Around 100 firefighters are currently at a blaze at Birmingham's last paper mill.
West Midlands Fire Service says more than 15 fire engines have been at the 150 year-old Smurfit Kappa plant in Nechells overnight.