Entry to the three ports, which serve ferry traffic to Britain, had been blocked by boats since Tuesday by fishermen who say that European Union quotas aimed at protecting dwindling fish stocks have been choking their livelihoods.

Michel Barnier, France's agriculture minister, refused at a meeting with fishermen on Wednesday to try to get the quotas increased, but offered $5.3m in aid.

French ministers point out that the last quota-setting European Union fisheries meeting in December agreed to a 30 per cent increase in cod catches in some parts of the English channel.

For years, scientists have said cod is so badly overfished in EU waters that it is in danger of extinction.

The European Commission has ruled out any further increase in quotas.