Pacific island trade deal signed in Tonga

Three of the Pacific's biggest players, PNG, Fiji and Vanuatu have boycotted a new free trade deal with Australia, New Zealand and other island nations.

There were some notable absences when Australia and New Zealand signed off on a free trade deal with eight Pacific Island countries at a ceremony in Tonga.

Three of the region's biggest island nations - Papua New Guinea, Vanuatu and Fiji - have snubbed the deal because of criticism it favours Australian and NZ interests.

Australia's assistant trade minister Keith Pitt travelled to Nuku'alofa for the occasion.

The deal, known as Pacer Plus, will support development outcomes by helping Pacific island countries trade regionally and globally as well as help foster a secure, stable and prosperous region.

It covers goods, services and investments and includes Cook Islands, Kiribati, Nauru, Niue, Samoa, Solomon Islands, Tonga and Tuvalu.

Negotiations wrapped up in April after eight years.

There is $50 million in development assistance allocated as part of the deal.