Fishermen threatened to block the harbour in Valletta, Malta
France has hit back at the European Commission for calling an early halt to industrial fishing of bluefin tuna in the Mediterranean Sea.
French Fisheries Minister Michel Barnier said he wanted the commission "to explain its decision in an intelligible way".
EU fisheries ministers are set to discuss the dispute on Tuesday.
On 13 June the commission said the bluefin tuna fishing season must end two weeks early, as stocks were low.
Mediterranean tuna is highly prized - especially in Japanese sushi cuisine, which is now a global success.
Fisheries Commissioner Joe Borg complained of "countless failures to properly implement the rules, which have been agreed at international level, to manage the bluefin stock sustainably".
The EU ban targets fleets from France, Italy and Spain
He said the commission was aware of eight French purse seine trawlers that had spent up to 21 days fishing since the start of the season, but had "so far declared no catches".
Eight similar Italian vessels had "according to official figures, overshot their quota by between 100 and 240%", he said.
He also complained that at least eight spotter planes had been assisting trawlers to locate bluefin tuna shoals, "even though the use of spotter planes is completely illegal".
Mr Barnier told the French weekly Le Journal de Dimanche that "the commission's figures are based on estimates or projections more than on facts".
He argued that at the moment of the commission's ban, "only 52% of France's quotas were full". France takes over the EU's rotating presidency next week.
On 17 June about 300 Italian and French fishermen protested in Malta over the commission's move and threatened to block the island nation's harbours if Commissioner Borg - himself Maltese - declined to hear their concerns.
'Risk of collapse'
The row follows protests by fishermen in several EU countries in recent weeks over the impact of high fuel prices, which they say threaten their jobs.
The environmental group Greenpeace says there is a high risk that the bluefin tuna stocks in the Mediterranean will collapse.
A Greenpeace fisheries expert, Sebastian Losada, told BBC News that "the number of boats is so big that within just a couple of weeks they can catch their whole quota - the current rules are insufficient".
He said there should be a ban on bluefin tuna fishing in May and June - the breeding season in the Mediterranean - and quotas "should be in line with what scientists recommend".
According to Mr Losada, some 50-60,000 tons of bluefin tuna is now caught annually in the Mediterranean and Atlantic, whereas the scientifically recommended catch is 15,000 tons maximum.
He added that Spain had "authorised its Mediterranean fleet to fish for undersized tuna, which is completely illegal".