Farmers and landowners are being warned to beware a scam in which household and business waste, camouflaged as plastic-wrapped hay bales, is illegally dumped on open land.
Environment Agency officers believe criminals are making huge sums of money by charging to take away rubbish before then dumping it in remote rural locations.
The compacted waste is built into haystack shapes to give the impression they are the "normal" hay-storing bags used by farmers.
The police warning follows the discovery of about 1,500 tons of waste after a search warrant was executed on land in south Essex.
Lesley Robertson, an Environment Agency environmental crime team leader, said: "The discovery of around 3,000 bales of rubbish in Essex is believed to be linked to a highly-organised criminal scam involving the disposal of household and business waste."
She added: "The waste includes all forms of household and business rubbish such as food waste, plastic and cans. They are being dumped and abandoned with total disregard for the environment, landowners and any member of the public who use the land.
"We urge any landowners, farmers, ramblers or dog walkers who find these sites to call us immediately on our 24-hour free incident hotline number 0800 80 70 60 or make an anonymous report to Crimestoppers on 0800 555 111."
Three men, aged 19, 23 and 47 and all from east London were arrested on suspicion of depositing and storing waste on an unpermitted site when police and the Environment Agency ambushed the Arterial Road site in Purfleet on April 10.
They are on bail until July 10.
