A search for a missing four-year-old boy will resume at an outback sheep station more than two weeks after the child disappeared.

Gus Lamont went missing at the Oak Park Station homestead, about 40km south of Yunta, in South Australia's Mid North region, on September 27.

The "shy, adventurous" pre-schooler's grandmother last saw him playing on a mound of dirt at 5pm.

He was nowhere to be found when she returned 30 minutes later.

SA Police have pledged to "never give up hope of finding Gus", with the search to resume on Tuesday.

Police and army personnel will look at a section of the farm not covered by the extensive search to date.

"The search ...will concentrate on an expanded area outside of the zone already searched extensively following Gus's disappearance," a police statement sa

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