A blaze at a site at the centre of a fly outbreak is being treated as arson.
Firefighters were called to the site off Nook Lane, Oswaldtwistle at around 2.15am on Thursday, August 2 after 100 bales of waste went up in flames.
Police, Hyndburn council and Environment Agency officers also attended the scene at the former NIPA Laboratories site.
Lancashire Fire and Rescue spokesman John Taylor said it was now being investigated as a probable arson by police.
He added: "We will contribute where we can in terms of forensic evidence."
Fly-tipped waste dumped at the site has been linked to an infestation of flies in the town, and is being investigated by the Environment Agency.