Solidified palm oil, which is poisonous to dogs, has washed up in a popular dog walking spot.
Lewes District Council said the substance had washed up between Newhaven eastern arm and Splashpoint, Seaford.
A council spokesperson said: “We are cleaning the area over the next couple of days and suggest that in the meantime all dog walkers ensure their dogs are on a lead.
“We are notifying the Maritime Coastguard Agency of the situation.”
Solidified palm oil is a white, waxy substance. Dogs also seem to like it and will eat it given the chance.
Newhaven Coastguard warned residents the palm oil could spread further along the coast.
It can cause vomiting and diarrhoea in dogs which can lead to dehydration. It is not toxic to humans. Palm oil previously washed up on the beach in February after a ship lost its load off the coast of Cornwall.