Ecuador has stepped up its fight against EU banana duties by asking the World Trade Organization (WTO) to rule on the issue.
Bananas have been the source of frequent trade disputes
Ecuador, the world's largest banana exporter, says it and other Latin American nations have to pay more than Caribbean and African (ACP) producers.
It first made a complaint to the WTO in November, claiming the EU duty regime brought in last year was unfair.
Brussels says the duties comply with an earlier 2001 ruling on the issue.
Ripe for reform?
The EU was forced to modify its arrangements for banana imports six years ago, after losing a case brought by Ecuador and backed by the US.
But Ecuador says the current system - introduced in January 2006 - denies it fair access to lucrative European markets.
It and other Latin American countries currently have to pay 176 euros ($225; £119) per tonne on banana imports.
In contrast, annual imports from the Caribbean and Africa are currently duty-free unless they exceed 775,000 tonnes. At that point, they are subject to the same level of duty.
The WTO's dispute settlement body will meet next month to discuss the issue, with a formal panel likely to be convened soon after to rule on the case.
Latin American countries have historically accused the EU of giving preferential treatment to ACP nations, often former colonies of France, Britain and Portugal.
The EU has described Ecuador's move as unhelpful.
"As far as we are concerned, we have done what we needed to do," said a European Commission spokesman.
Ecuador accounts for about a quarter of all banana exports to Europe and the US.