Police are searching new locations in Waikato for missing father Tom Phillips and his three children

They're moving their focus to areas including Honikiwi and Otorohanga - after three days of operations in Marokopa, which are now being scaled back.

Police say a number of credible reports have come through after offering an 80 thousand dollar reward for information earlier this week.

Police believe Phillips is being helped to stay hidden and are offering possible immunity for anyone doing so.