A man has been arrested on suspicion of arson following a fire at the former A1 Supa Skips site in Lancaster.
The man, 36, was arrested at an address in Lancaster on Wednesday and has now been bailed, said police.
A multi-agency response to the fire, which broke out in the early hours of Sunday morning (December 3) at the former skip hire site and power station at Port Royal Avenue, Lune Industrial Estate, is continuing.
Caroline Harrison, group manager at Lancashire Fire and Rescue, said on Wednesday: "We are continuing to fire fight at the scene and we are dealing with a fire that involves approximately 13,000 tonnes of commercial waste.
"The main building is structurally unsafe and this poses a risk to our emergency response teams.
"Our priority is to extinguish the fire and work closely with the Environment Agency to minimise any potential environmental consequences stemming from the water run-off.
"The seat of the fire lies between extensive layers of densely packed commercial waste and this makes it difficult for us to get the persistent pockets of fire that can endure for an extensive period. Consequently, the fire continues to produce a visible smoke plume and we strongly advise residents to keep their windows and doors closed if they can smell smoke.
"As a result of this incident, several roads including Europa Way are temporarily closed and access to the industrial park is restricted as emergency operations are expected to persist for several days.
"We kindly ask the public to steer clear of the affected area. This request is not only for their safety but also to prevent any hindrance to our emergency efforts.
"We are continuing to work with Lancaster City Council, the Environment Agency, Lancashire Constabulary and Lancashire County Council and we remain focussed to bring this incident to a safe conclusion as swifly as possible while minimising disuripton to the local community.
"Finally I just want to say thank you to the residents and businesses for their support since Sunday."