Fifty-two survivors have been recovered following the sinking of the inter-island ferry Princess Ashika, near Nuku'alofa, Tonga, late on August 5.
However, initial reports that the ferry was carrying 75 people have now been updated to 79 people, leaving 27 still unaccounted for.
A Royal New Zealand Airforce (RNZAF) Orion is currently searching the area, with a second Orion scheduled to leave Whenuapai at 8.30am to relieve it. Its ETA is around midday today. Three vessels, including the Tongan Navy vessel, the Pangai, are also on scene assisting with the search.
The Rescue Coordination Centre New Zealand (RCCNZ) launched the rescue response after the Maritime Operations Centre (New Zealand Maritime Radio) picked up a mayday call from the Princess Ashika just before 11pm yesterday. A few minutes later, RCCNZ received a distress beacon alert from the vessel, which was heading from Nuku'alofa to Ha'afeva, in the Nomuka Islands group. The ferry is reported to have sunk about 46 nautical miles (86km) north east of Nuku'alofa.
It is unknown at this stage what caused the ferry to sink.
RCCNZ Search and Rescue Officer Mike Roberts said the RNZAF Orion was searching an area of around 80 square miles, with about 5 per cent of this area now covered. Another merchant vessel had also been diverted and was expected to arrive about 11am to assist in the search for survivors.
Roberts said the top priority for rescuers was to find and account for those missing as soon as possible.
Weather in the area is moderate with 25 knot winds and a 2-3 meter swell, which is forecast to ease. Water temperature is approximately 25 degrees Celsius.