A lifeboat was launched to reports of a jet ski in difficulty on Sunday – in what crews now fear was a hoax call.
Newhaven’s Severn Class lifeboat and crew were called after a call from a jet skier saying he had broken down in the Saltdean area at around 11am, said the RNLI.
Brighton’s inshore lifeboat joined the extensive search around the coastline but nothing was found.
The RNLI said it is now thought it was a hoax call, one of a number received from the area in recent years.
Coxswain Paul Legendre said: “Although we will always assume that any call is a real emergency and we will conduct a full search, we are becoming very concerned as this is another hoax in the same area.
“Our biggest fear is that one day Coastguards and lifeboats could be responding to one of these hoaxes and someone genuinely in trouble may lose their life.”