The World Trade Organization on Tuesday gave Mexico the green light to impose $160 million in annual tariffs against the United States in retaliation for Washington's discriminating against Mexican tuna imports. The long-running tuna trade feud between the North American neighbours centres on the controversial "dolphin safe" label.

For more than two decades the United States has required all tuna imports to be certified "dolphin safe", part of a campaign to save a species that had been decimated by fishing nets. But Mexico argues that the US applies stricter standards to its exporters to acquire the "dolphin safe" certification than to those from other countries. A 2015 WTO ruling agreed that the US had inaccurately evaluated the risks to dolphins posed by Mexican tuna fleets. The Geneva-based WTO, which aims to ensure a level playing field in global trade, cannot force countries to change their trade policies.

But it can authorise retaliatory measures against countries that do not comply with its rulings. Tuesday's decision follows the US refusal to adjust its labelling of Mexican tuna. A WTO arbitrator authorised Mexico to hit US exports with $163 million (149 million euros) in annual tariffs in response. But the dispute looks set to carry on.

Last year, Washington amended its tuna labelling guidelines, applying the tougher standards applied to Mexico to all importers. If the WTO ultimately decides that the US is now treating all nations equally, its previous 2015 decision would be quashed. Further complicating the case is a threat from US President Donald Trump's administration to disregard WTO rulings that hurt American trade interests.

Copyright Agence France-Presse, 2017