CONTROLLED burning took place in the open on Rhyd Y Foel Mountain on Tuesday morning.
North Wales Fire and Rescue service said they received a call at 9.26am.
A farmer is in attendance monitoring.
A spokesperson from North Wales Fire and Rescue said: "It is controlled burning by a landowner.
"One crew from Abergele attended and one officer attended."
An eyewitness said he spotted thick smoke towards the back of Gwrych castle this morning.
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