A New Zealand Defence Force P-3 Orion has been pulled off fisheries patrol to search for three Kiribati fishermen missing since Saturday.
The men were last seen on a 5m boat early on Saturday morning leaving Betio, the largest township in the Kiribati capital, Tarawa.
Air Force spokesman Air Commodore Darryn Webb said the men were expected home on Saturday afternoon and local searches have failed to find them.
He said the Orion planned to search a wide area.
"The search area is in excess of 30,000 square kilometres. So a big area and the combination of winds and tides mean that area gets bigger and bigger every day.
"So if we have no success [by] tonight we will stay in Kiribati overnight and recommence as fresh tomorrow."