A whale carcass has washed up just south of Cottesloe Beach this morning closing all beaches in the area as authorities warned people to stay out of the water following sightings of sharks.

The sighting was reported to Fisheries at 6.15am, with a juvenile whale carcass washing ashore at Dutch Inn Beach in South Cottesloe.

Surf Live Saving WA confirmed that lifeguards closed Cottesloe Beach around 7.30am on Thursday, with a shark alert also being issued due to the presence of the carcass.

The Town of Cottesloe confirmed the beach closures on its Facebook page on Thursday morning.

“All Cottesloe Beaches are CLOSED due to shark sightings and the presence of a beached dead whale near Dutch Inn,” the page read.

“Rangers have immediately closed beaches from BEN sign CT1 to BEN sign CT54.

“Please stay out of the water.

“This closure INCLUDES Cottesloe main beach with the shark barrier.”

SharkSmart issued an alert urging the public to exercise extra caution in the area.

“It is possible the carcass will act as an attractant that could lead to sharks coming in close to shore along this stretch of coast,” the alert read.

Shark activity can be monitored on the SharkSmart website and any shark sightings should be reported to Water Police on 9442 8600.

It comes just three weeks after a 31-tonne humpback whale carcass caused havoc at City Beach after it washed ashore and attracted multiple great white sharks to the beach.

It took several days and $180,000 to remove the carcass, with surrounding beaches in the area remaining closed for more than a week due to the shark risk.

More to come.