Image source, WA POLICEImage caption, Cleo Smith has been missing from the beach campsite since Saturday

Australian police say they have "grave concerns" for a four-year-old girl who disappeared from a remote, coastal campsite four days ago.

Cleo Smith was last seen sleeping in her family's tent at the Quobba Blowholes camping ground in Western Australia on Friday night.

She was missing the next morning when her mother woke up, police say. Her sleeping bag was also gone.

An extensive air and sea search is continuing.

Police made an appeal on Monday for any information and for other visitors to the campsite to come forward, increasing national attention on the case.

Western Australia Police shared pictures of the girl, as well as images of her sleep suit and her sleeping bag.

Have you seen four-year-old Cleo Smith?

Cleo was last seen at 1:30am, Saturday 16 October 2021, in a tent at the…

Posted by Western Australia Police Force on Monday, October 18, 2021The BBC is not responsible for the content of external sites.View original post on Facebook

Authorities have not disclosed any information on what they think happened to the girl, but have said they will "leave no stone unturned".

Australian media reported that Cleo's family had travelled to the remote site, about 900km (560 miles) north of Perth, on the weekend for a camping trip.

The Quobba Blowhole site, in Macleod, is a local attraction on the state's Coral Coast – known for its windswept ocean scenery, sea caves and lagoons.

Image source, WA POLICEImage caption, A large air and sea search is underwayImage source, AbcImage caption, Extra police officers have been deployed to the area from Perth

On Tuesday, police crews were seen scouring the deserted white beaches and scrubby bush for signs of Cleo. Private helicopter services also joined the search.

Police said they had focused their search on a row of shacks near the coastline.

By late Monday, they had scaled back their search efforts from the water, local media reported.

Authorities were due to give an investigation update later on Tuesday.