A ferry with 79 people on board has sunk off the coast of the Pacific Island nation of Tonga, with 27 people reported missing, Radio New Zealand International reported on Thursday.

A major search and rescue operation was launched Wednesday night after a mayday call was received from the inter-island ferry, Princess Ashika, which said it was sinking.

The first boat on the scene found 42 people on life rafts.

The New Zealand Rescue Coordination Center said 52 crew and passengers of the Princess Ashika have now been picked up after the vessel went down Wednesday night.

A New Zealand airforce Orion plane has been sent to the scene -- and a fourth ship is on the way to assist.

The ferry was heading from Nuku'alofa to Ha'afeva, in the Nomuka Islands group.

(Xinhua News Agency August 6, 2009)