The police helicopter and checkpoints are being used in Marokopa in the search for Tom Phillips and his three children.

Police announced an $80,000 reward yesterday - and say they've had an increase in emails, calls and visits since.

Waikato Herald reporter Maryana Garcia says police are stopping cars going in and out of the town and the chopper has been up all day.

"The chopper's been flying over the Marokopa area, it came through this morning and it did a loop around that coastal area."

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