South Australian Police have completed their latest search for missing four-year-old Gus Lamont, finding nothing in mineshafts near his remote home.

Police launched the latest search for the small boy on Tuesday.

It involved searching six mineshafts and several other locations up to 12 kilometres away from Gus’s home in SA’s mid-north. They were identified following analysis of aerial mapping and imaging conducted following recent ground searches.

Gus was last seen by his grandmother in the late afternoon of September 27, playing on a mound of dirt outside his family home, a sprawling sheep station in South Australia’s Mid North.

He has not been seen since.

No sign has been found of four-year-old Gus Lamont in a search of mineshafts. Photos: SA Police

Intensive searches comprising hundreds of police, SES members, mounted units and even the Australian Defence Force have spanned 470 square kilometres near Oak Park Station and also involved aerial support. All have failed to find the young boy.

This week’s search involved officers from STAR Group and Task Force Horizon, who used specialised equipment to search the mines.

The uncovered and unfenced shafts are between 5½-12 kilometres from the remote Oak Park homestead, which is about 40 kilometres south of Yunta in South Australia’s mid-north.

Police said they were not previously aware of the location of the sites.

“The inspection of the mine shafts … did not locate any evidence to assist in the investigation into Gus’ disappearance,” SA Police said.

“Several of the shafts were relatively shallow and could be visually inspected but the remainder were up to 20 metres deep and specialised equipment was required to complete the searches.”

Other locations being search on foot on Wednesday were up to 10 kilometres from the homestead. Police said they were outside the 5½-kilometre radius that had already been extensively searched.

“The family of Gus have been advised of the results of the renewed searching and are being supported by a victim contact officer,” they said.

“Task Force Horizon officers have not ruled out returning to the property as the investigation continues.”

Earlier, SA Deputy Police Commissioner Linda Williams said the force would not stop searching until every avenue had been explored.

In late October, police drained and searched a dam in late October, ruling out the possibility Gus drowned on the property.

It took about 3½ hours to drain 3.2 million litres of water from the 4.5-metre-deep dam, which is 600 metres from the homestead. Nothing “of significance” was found, they said.

The water was then pumped back into the dam.

An initial 10-day air and ground search for the missing boy was one of the largest undertaken by SA Police.

Gus’s family members have “continued to co-operate fully with police and are being supported by a victim contact officer”, police said.

-with AAP