The World Trade Organisation says Tonga will become its 151st member on July 27
Tonga has a population of about 117,000 and its accession was cleared by the world trade body in December 2005 but needed government approval to become final.
The ratification was deposited with the Geneva-based WTO yesterday and automatically becomes effective one month later.
Farm goods such as squash, coconuts, bananas and vanilla beans make up two-thirds of Tonga's exports.
