An SOS sign made out of rocks has been spotted in a remote part of Western Australia, sparking fears someone - or some people - could be missing.

How old the sign is, is hard to tell. There are indications someone may have camped nearby.

The distress signal was spotted by a helicopter pilot last week in an area known as Swift Bay, about 120 kilometres west of the Kalumburu Aboriginal Community in the Kimberley region.

It's more than 1000 kilometres by vehicle north of Broome, deep in four-wheel-drive country.

Police were only able to access the site with the help of a helicopter charter company, according to the ABC.

Officers have searched the area but found no clues to the sign's maker.

They are trying to establish if there are any missing persons in the area.

No one has been located thus far, but there are indications that someone may have camped near the sign.

The finding has puzzled local Kalumburu police, leading to calls for public assistance.

"We've done a ground search and aerial search of the area and there are indications that there may have been someone camped there at one point in time, but it's just not clear how long ago that was," Senior Sergeant Peter Reeves told ABC Radio.

"We're asking for anyone, if they have any knowledge of the person who may have been in distress and may have made that sign, if they can contact us.

"Likewise, if they know of anyone who is in distress who may be out in that area, that we've got an idea of who and what we may be looking for."

Anyone with information is urged to call Crime Stoppers on 1800 333 000.