There have been 12 incidents on Dartmoor in the past week.

Even Cadover Bridge, one of Dartmoor's most popular beauty spots - has been hit.

A pile of broken black slates, plastic tape and bottles, cardboard and rubble lies by the river.

Ponies are at risk from rubbish

National Park Rangers have cleaned up three tonnes of rubbish in the past seven days.

Head ranger Rob Steemson, said: "The effect on the moor is terrible.

"We are looking after one of the best areas in the South West and this is really quite frustrating that people are coming out here tipping their household waste and litter on the moor.

"That kind of attitude in an area like this is quite atrocious."

Mandy Hand, who has been riding on the moor for many years, said horses and Dartmoor ponies were in peril.

Increasing problem

She said: "Horses will eat anything that is edible. And they can be injured on nails that are sticking out from all this rubbish."

The Environment Agency says fly tipping is an increasing problem.

Much is due to people trying to avoid the £13-a-tonne charge for disposing of business waste in landfill sites.

The agency asks anyone who sees fly tipping to report it on freephone 0800 80 70 60, and it will prosecute.

The fines can be up to £20,000.