More than 20 explosive distress flares were found buried on a beach in Brighton.
A member of the public reported finding a couple of the flares on a beach east of Brighton Marina.
Seafront staff from Brighton and Hove City Council searched the area and found 21 of the flares.
They called the Coastguard, who removed the flares for safe disposal, and reported the incident to Sussex Police.
The council said: “Boat owners are being urged to dispose of out-of-date distress flares carefully to avoid endangering the public.
“Seafront staff are also warning people to look out for dumped flares.
“Flares are typically red and yellow cylinders about the size of a toothpaste tube but other shapes and colours exist.”
Anyone wanting to dispose of flares should contact the Coastguard on 02392 552100.
Seafront officers said that the devices were potentially highly dangerous.
Each contains an explosive charge designed to shoot a flare up to 1,000ft into the air.
Council seafront operations manager Viki Miller said: “Flares are extremely hazardous if handled incorrectly or disposed of inappropriately.
“It is essential boat owners take responsibility for the safe disposal of these devices to ensure they do not harm others.”
Anyone finding a flare on a Brighton beach can also contact the seafront office on 01273 292715.