
A special WTO group on the issue discarded arguments from Cuba, the Dominican Republic, Honduras and Indonesia, a statement said.
The so-called "neutral" packets were introduced in Australia in December 2012 with the aim of deglamourising smoking.
The packs are an identical olive green, bearing no logos and instead including health warnings.
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In 2014, Cuba, the Dominican Republic and Honduras, all major tobacco producers, as well as Indonesia launched separate complaints before the WTO, saying the Australian legislation harmed their business.
Ukraine also filed a complaint, which it later withdrew.
WTO experts said the countries had failed to show that Australia's actions contravened international law or blocked international trade.
They also rejected the charge that neutral packets do not reduce tobacco consumption.
The WTO decision will take effect within 20 to 60 days, barring an appeal.
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