An official French report on the break-up of the oil tanker Prestige off the coast of Spain a year ago has severely criticised the Spanish authorities, saying their actions during the crisis made matters worse rather than better.

The judicial report was commissioned by French parliamentarian Philippe de Villiers, a senior political figure in the Vendee region whose coastline was partly spoiled by heavy fuel oil slicks that seeped from the Prestige.

The Spanish government prevented emergency crews from going aboard the stricken tanker to try to prevent the disaster until they agreed in writing to tow it out to sea, “whereas good sense should have told them to bring it into the port of La Coruna,” said the report.

The Prestige sank on 19 November last year, after drifting for six days off Spain’s north-western Galician coast. Some 50,000 tonnes of oil leaked into the sea.

De Villiers said he would begin legal action against the Spanish government in view of the enormity of Spain’s liability revealed by the report.

French President Jacques Chirac said Europe must do more to protect its coasts from devastating oil spills similar to the Prestige disaster.

The EU last month adopted rules banning single-hull tankers carrying heavy fuel oil from EU ports, yet despite the new legislation, nothing can in principle prevent an old tanker passing through the English Channel between Britain and France, as long as it does not dock.