Maritime New Zealand is investigating whether a mayday call from a boat reported missing south-east of Whangarei was a hoax.
The call, at 1.20am on Friday, said the East Coaster with four people on board, was taking on water near the Hen and Chicken Islands.
Contact was then lost and a Coastguard boat and navy vessel began a search, joined about 9am by a helicopter and a plane, which covered an area of about 150 square nautical miles.
The Search and Rescue Co-ordination Centre suspended the search about 2pm and there has been no contact with the boat since the initial mayday call.
A further search may be carried out if any new information comes to light.
Heavy rain, visibility reduced to 10 metres, winds of up to 30 knots and swells of up to three metres on Friday made the search difficult.
Search and Rescue says any wreckage would have been seen by now and there have been no reports of anyone missing.
