Beachgoers are being warned not to touch a ‘solid waxy substance’ which has been found on some parts of the coast.
A spokesman from the Littlehampton Coastguard said the team found the substance along the coastline between Bognor Regis and Ferring while investigating reports of pollution in the area on Sunday.
The heaviest quantities of the substance, which is ‘largely yellow in varying size lumps’, was found around Rustington and East Preston.
The spokesman said: “We do not know the source of the substance, or what it is.
“We have seen some posts suggesting this is palm oil, we must stress that this is not confirmed at this time and we ask people not to speculate.
“Our advice to members of the public is not to touch the substance.
“We also urge people to keep their dogs away from any yellow or white waxy substances.”
Sample of the substance have been gathered, the spokesman said, and the Maritime and Coastguard Agency counter pollution will be made aware.
Arun District Council confirmed it had received reports of the substance on the beach.
“This will wash away with the tides but in the meantime we encourage dog walkers to be vigilant and keep dogs on leads and away from anything suspicious,” a council spokesman said in a tweet.