The Environment Agency (EA) discovered 11 illegal waste sites during a one-day sting operation in Lincolnshire and Northamptonshire last week.
Officers found six sites where waste had been burnt, a further three containing construction and demolition waste, one containing household waste, and one scrapyard – all operating illegally.
According to the agency, officers discovered items including furniture, plastic, insulation, car parts, fuel containers and chimney-sweeping equipment.
Out of the 28 sites visited by officers, 17 were found to be operating within the law. The EA said the illegal sites will now receive written guidance clarifying the steps they must take, and follow-up visits will be arranged to make sure the site operators comply.
Mark Rumble, enforcement team leader with the EA, said the agency would “continue to monitor local reports” and that evidence gathered from the visits will be used against those breaking the law.
If convicted of illegal waste activity, he said, offenders face unlimited fines and up to five years in prison.