Palm oil is washing up on beaches across the country in "bergs" as councils issue warnings about the deadly effect the substance can have on dogs.

Dog walkers have been told to remain vigilant and not let their animals lick the white clumps of oil which litter the coast of Norfolk, Wales and Cornwall.

Concerned residents in North Norfolk have reported finding the substance on many beaches including Cromer, Sheringham and Sea Palling.

Ships are permitted to dump palm oil into the sea if they are at least 12 miles offshore.

The lumps of oil, which can weigh up to a quarter of a ton and originate from palm trees, can harbour many germs and diseases.

While some travel 3,000 miles across the ocean from the Caribbean, other waste is dumped overboard by cargo ships as they swill out their holds at sea.

These wreak environmental havoc, and have been blamed for the death of a gannet in at Pendeen on the Cornish coast.

Dog walkers at Fistral in Newquay have been warned not to touch the toxic material. A post on the Fistral Beach Facebook page reads: "We have just been informed by the lifeguards that palm oil has been washing up on the beach.