Landowners are being urged to be on their guard against illegal waste operations, which may cost them thousands in clean-up costs.
The Environment Agency issued the advice after investigating officers discovered large-scale tipping of waste in Sheffield and Leeds, at three sites where waste permits are not in place to allow such operations.
In each case a waste operator negotiated access to the sites by signing leases for their use.
More than 1,000 tonnes of waste was then dumped across the three sites, without environmental permits being in place.
The waste operators have since disappeared.
Andy Swettenham, environment management team leader at the Environment Agency, said: “If you own or lease out land for industrial use, it is vital that you know what activities are taking place on it.
“If your tenant uses or intends to use your land for waste activities, they must possess all of the appropriate legal permits, and the responsibility lies with you to ensure that those waste activities are legal.
“ If you fail to check and illegal waste builds up on your land, then you could be liable for the costs of having it removed and the land restored.
“Anyone who believes any illegal waste activities are taking place is urged to report the matter to our incident hotline.”
Anyone or any business which transports, treats, stores or deposits waste without the required environmental permits is breaking the law.
And if waste is left illegally on any land, the responsibility for removing it can fall to the landowner or property landlord.
Report offenders on 0800 807060 or Crimestoppers on 0800 555111.