In the darkness of the Indian Ocean, a bulky French refuelling vessel looked like easy pickings for two boatloads of Somali pirates as they drew alongside early yesterday.

The brigands had started their usual pre-boarding drill, letting loose with Kalashnikov assault rifles, before they noticed the 40mm cannon and missiles on the deck above them. The fat merchant ship was, in fact, La Somme, the 18,000-tonne flagship of the French naval operation that has been launched against the pirates.

“They understood their mistake too late,” said Admiral Christophe Prazuck, as he recounted the second misguided assault on a French warship by bungling pirates in recent months. In May, pirates mistook a French frigate for a cargo ship and were immediately captured, while two months earlier another group tried to take on the Spessart, a German Nato supply ship.

Yesterday’s attackers turned tail as soon as they realised what they were up against and La Somme, a refuelling ship and command vessel, followed in hot pursuit. She caught up with one of the boats after an hour and the five crewmen surrendered without a struggle. The second boat escaped, but other warships in the area have taken up the search.

Other ships are on the lookout for another pirate group which attacked a cargo vesssel off the Seychelles on Sunday.

Yesterday’s blunder was further evidence that the pirates remain poorly organised and lacking in technology, despite reports that they have been developing more sophisticated methods. “They must be on the dim side if they can’t tell a frigate from a freighter,” said a French officer.

With a crew of 170 and under the orders of an admiral, La Somme commands French air, sea and land forces in the combined US and European campaign against piracy and terrorism in the region. The vessel supplies ships and aircraft and has been the base for French commando operations to free hostages from pirates over the past two years.

At least 163 attacks have been staged by Somali pirates this year, 47 of them successful hijackings, according to monitoring agencies. Last year more than 130 merchant ships were attacked.

The pirates, who come mainly from villages in Puntland, the lawless Somali province, have lost as many as a dozen of their comrades in attacks by French and US navy commandos. In April, US snipers killed three pirates when they freed the captain of the Maersk Alabama, but days earlier, a French yacht captain was shot dead by French commandos as they stormed his craft. His wife, child and a crewman were rescued.

The US Maritime Administration warned last month that the end of the monsoon season was likely to bring an increase in piracy off Somalia.

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