A search is underway Saturday night off the coast of Fiordland for a fishing vessel with two people on board.
Police said another fishing vessel found a fuel slick some 3km from the mouth of Milford Sound about 5pm on Saturday.
They said an empty inflatable life raft was found 12km further on, about an hour and a half later.
A life ring and other items were also found.
Police said the search had so far involved three fishing vessels as well as two helicopters equipped with night vision goggles and thermal imaging equipment.
They said bad weather reduced visibility, grounding the helicopter crews about 8.30pm Saturday night, but the three vessels were continuing to look.
The police said a fixed wing aircraft from the Coastguard would join the search Sunday morning.
They would not name the missing vessel nor the people on board until their families have been notified.