A search is underway for two people aboard a twin-engined aircraft that ditched in the sea off Kawhia after reporting engine failure.
The plane was reportedly registered to 2Degrees CEO Eric Hertz.
The emergency call was made about 12.20pm.
Rescue Coordination Centre (RCC) sent the Westpac Helicopter from Auckland to investigate the last known position of the aircraft.
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It found an oil slick and wreckage about 11 nautical miles (20km) north west of the entrance to Kawhia harbour, near Gannet Island.
The aircraft was a twin-engine Beechcraft Baron and was travelling from Ardmore to Timaru.
No details were known about the people onboard.
RCC Search and Rescue mission controller John Dickson said the aircraft radioed Airways New Zealand to report engine failure shortly before radar contact was lost.
"A helicopter from Phillips Search and Rescue in Hamilton is searching the area, along a fixed-wing Coastguard aircraft, and a Raglan Coastguard vessel is also on scene and is picking up debris,'' he said.
"Unfortunately there has been no sign found of the people onboard.''
The water in the area is about 60m deep.