The search for a missing four-year-old boy in South Australia’s north has entered its fifth day, after police continued to search overnight.

Gus was last seen playing in sand at his family’s remote sheep grazing station on Saturday about 40km south of Yunta.

Yesterday, a statement was released by the boy’s family in which they said they were “devastated by the disappearance of our beloved Gus”.

In the statement — which was read by family friend Bill Harbison, who went to school with Gus’s grandparents — the family said they missed Gus “more than words can express”.

“Our hearts are aching and we are holding onto hope that he will be found and returned to us safely,” they said.

A man in a cap and glasses.

Bill Harbison is a friend of the family of four-year-old Gus, who went missing near Yunta. (ABC News: Daniel Taylor)

Police are confident Gus was on the property and had not been taken, so a photo of the boy has not been shared, but police have released an image showing the shirt he was wearing.

Superintendent Mark Syrus said there had been no clues discovered about what direction Gus had gone in, but there was still hope he would be found.

On Tuesday morning, he told ABC Radio that police aircraft including drones and a helicopter equipped with infrared and thermal imaging cameras had been conducting searches.

A navy blue long-sleeve shirt with a yellow one-eyed 'Minion' on the front

SA Police shared an image of a ‘Minions’ shirt which is similar to the one four-year-old Gus was wearing when he went missing. (Supplied: SA Police)

He said teams on the ground had been “looking for clues of which way he might have gone, and then we can just move our efforts into that area”.

“The field search controller’s job is to look at the terrain, look at the personnel and then to segment areas and then to allocate them to search teams,” he said.

“They’ll put them into a line and then they’ll actually walk across the countryside so they’re actually looking under the bushes in that search area.

“It’s called a ‘contact search’, it’s pretty thorough and we’re just looking for clues — footprints, hats, anything he might have discarded.”

ABC reporter Bethanie Alderson has been on the scene since Monday and said authorities were working in trying conditions.

“The enormity of the sheep station hits you as soon as you arrive, with blue bush scattering the red dirt as far as the eye can see,” she said.

“The only sign of its end is the blue, rugged peaks on the horizon. The beginning of the Flinders Ranges.”

Taken from drone overhead, shows vast dessert terrain spotted with bushes and a rugged cliff skyline

The terrain around where Gus was last seen is vast and rugged (ABC News: Daniel Taylor)

She said areas that appeared flat and smooth at first glance were deceivingly rugged and hilly terrain.

“The arid scrubland is laced with winding sandy tracks, which reveal hidden crevices and dry creek beds at almost every turn.”

She said the area was dusty due to high winds, further stirred by those searching the property on motorbikes.