The urgent search continues for a father and his two young sons missing in outback Queensland, as fears mount over their safety.

Steven Van Lonkhuyzen and his two boys were last seen refuelling their white Mitsubishi Pajero in the Western Downs town of Miles, in the middle of a road trip to Cairns.

They were due to arrive in Cairns five days ago and it is feared they became stranded following widespread rain.

Police now worry the family would be running low on supplies.

"That's out greatest concern, that if they are stranded on some western block that they'll run out of food," Owen Elljoy of Queensland Police said.

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