CALAIS (AFP) - French fishermen disrupted shipping in the Dover Strait and blocked access to an oil refinery on Friday as anger over high fuel costs reached fishing industries in Belgium, Spain and Portugal. About 40 trawlers formed a cordon at sea in a protest dubbed "Operation Snail" to slow down traffic through the Dover Strait, a busy seaway used by some 600 vessels a day between the Atlantic and the North Sea. In Dunkirk, fishermen set fire to crates and set up roadblocks to prevent trucks from entering the Total oil refinery where riot police were deployed to secure the entrances, said an AFP correspondent. Fishermen ransacked fish stands at two wholesalers in Normandy and at supermarkets in the southern Narbonne region in protest at sales of imported fish. Two days after President Nicolas Sarkozy's government announced 110 million euros (173 million dollars) in aid, protests continued as fishermen ignored calls from their industry representatives to go back to work. In neighbouring Belgium, hundreds of fishermen handed out a tonne of fish for free at the main fishing port of Zeebrugge and warned of more protest action if their demands for compensation were not met. Anger mounted in Spain, Europe's fishing powerhouse, where fishermen's unions called for a rally in Madrid next Friday to protest against high fuel costs and the low price of fish. Trawler crews threatened to launch a nationwide strike in June if the Spanish government continued to turn a deaf ear to their demands, said Jose Antonio Suarez, spokesman for the fishermen in Vigo. "We are asking for similar measures to those taken in France, with reductions in charges or taxes," he said. Portuguese fishermen announced a strike starting next Friday to press demands for aid, but the government ruled out subsidies, saying they were not the answer. Like their counterparts in France, the fishermen in Belgium, Spain and Portugal say soaring oil prices have punched a hole in their operating costs, jeopardising their livelihoods. In France, the protest movement began on May 10 in the Atlantic ports near La Rochelle and quickly spread to northern France and the Mediterranean, six months after fishermen blocked several ports to demand compensation. The fishermen escalated their protest this week, disrupting cross-Channel ferry services and blocking fuel depots, ports and marinas. Agriculture and Fisheries Minister Michel Barnier travelled to the western city of Rennes to defend an aid package aimed at helping the industry cushion the cost of fuel, which has soared from 40 euro cents a litre to 75 in six months. "I believe that this plan has nothing in common with what has been done in the past. It is an urgent response to the need to modernise French fisheries," said Barnier. The French government was facing questions from the European Union, which expressed concern that the aid package to the fishermen may contain a form of disguised subsidy to businesses. But Prime Minister Francois Fillon said the European Commission had approved the plan, although an EC spokeswoman in Brussels cautioned that this was an agreement in principle. After meeting in La Rochelle, fishermen decided to keep up their strike action and a blockade of a fuel depot, the head of the local fishermen's association Pascal Henaff said. About 40 fishermen occupied the offices of the regional Finistere administration in the Brittany city of Quimper, while boats sat idle in the port of Guilvinec where crews went on strike. In Caen, about 100 fishermen ransacked the fish stands of two wholesalers and staged a protest that disrupted traffic along a motorway in Normandy, police said. Three supermarkets were raided in the southwestern Bordeaux region late Thursday and fishermen clashed with truckers loading fish at the port of Arcachon, local officals said.