The fire has forced road closures on the C403 and C415 to Cambois with diversions currently in place.
Firefighters are also warning that drifting smoke is also causing poor visibility on the A189 spine road.
A spokesperson for Northumberland Fire and Rescue Service said: “Our fire crews are tackling a major fire at a recycling plant at West Sleekburn.
The C403 and C415 roads to Cambois have been closed and diversions are in place.
Drifting smoke is also causing poor visibility on the A189 Spine Road. Please reduce your speed, close windows and put headlights on if you are travelling along this stretch of road.