Fire at Atlantic recycling site at Rumney, near Cardiff
Over 20 firefighters are continuing to tackle a blaze involving 2,000 tonnes of waste material at a recycling centre on the outskirts of Cardiff.
The incident at the Atlantic recycling site in Newton Road, near Rumney, began at 01:30 GMT on Friday with 70 firefighters brought in at one point.
South Wales fire service said the blaze, involving plastic and timber, would take "days not hours" to tackle.
Residents are being advised to keep windows closed overnight due to smoke.
The fire service said its work is being hampered by 30 to 40 gas cylinders which firefighters are having to keep cool for fear of possible explosion.
South Wales Police said the site was five acres in size containing 10,000 tonnes of waste and there was a 200m exclusion zone in place because of the gas canisters.
Residents in the area are advised to keep their windows and doors shut as a precaution but the smoke is not considered hazardous.
The cause of the fire is not known but an investigation is taking place.
Pete Jenkins, the fire service's commander at the scene, told BBC Radio Wales: "There are a number of unknown gas cylinders involved in the fire which has presented a serious risk to firefighters.
"Our efforts up to now have been concentrating on cooling those cylinders to try to reduce the risk to firefighters on the scene."
Mr Jenkins said the site was fairly isolated and the closest homes were outside the exclusion zone.
He added: "The fire is surrounded [by fire crews] on three of four sides at the moment and we're supplying a lot of water to the fire.
"There is a large quantity of unburned material as well that we're working hard to prevent catching fire.
"We're confident we'll be able to deal with the incident but because of the nature of the recycling materials and the actual amount on site, I envisage this incident will take a number of days rather than hours."
Up to 20 fire appliances have been at the scene, including a high volume pump which was brought in to draw water from nearby ponds and drainage ditches.
Gareth O'Shea, of Natural Resources Wales, said: "The priority at the moment is for the South Wales Fire and Rescue Service to extinguish the fire.
"Our officers are at the scene advising the firefighters about the nature of the waste on the site so they can determine the best way to tackle the blaze."