Police have attended the scene of a fire just outside Adlington.
The incident happened on Sunday afternoon (February 18) near to Waterford Close in Heath Charnock.
In a statement on Facebook, Chorley Police said: "There is a large plume of smoke visible from Chorley and this is the cause.
"We believe the fire to be suspicious. We will be treating this as arson at this stage."
The object on fire is believed to be a set of wooden steps.
A police spokesman added: "Quite a few trees are also alight although the fire isn't spreading due to the typical British weather."
Further updates are expected.