Crews were called to Atlantic Crescent at about 2340 GMT on Sunday and at the height of the fire, 22 appliances were at the scene.

The fire, which is now under control, is still burning and it is not expected to be extinguished for some hours.

It is not known how the blaze at the single storey unit started. No-one has been injured.

Several factory units and workshops were housed inside the building, which is said to be "severely damaged".

Station Officer Mike Boss from South Wales Fire Service said: "A forensic investigation team are coming in to try and find the cause of the fire.

"There is a lot of damage here, the roof has collapsed and it will be at least another 24 hours before it is made totally safe.

"There have been about 70 to 80 personnel here trying to get it under control."

Crews had to withdraw from the scene to a safe level after the risk of explosion from an unknown quantity of LPG cylinders which are being stored in the units.

Firefighters are cooling the cylinders from a safe distance using hydraulic platforms and ground monitors.