Hours after President Obama promised to halt the rise of piracy off the Horn of Africa, Somali gunmen gave their response, hijacking two more vessels and opening fire on a third yesterday.

It also emerged that they had seized two Egyptian fishing boats a day earlier, making a total of four vessels and more than sixty crew captured in little more than 24 hours of plunder.

A flotilla of warships patrolling busy shipping lanes has repelled several attacks but has not been able to prevent 18 successful hijacks this year.

US navy personnel shot dead three pirates on Sunday to rescue an American container ship captain being held hostage on a lifeboat. Two more pirates — and a hostage — were killed on Friday during a French operation to free a captured yacht. The deaths and warnings of further action have made no impact so far on the gangs and their hunt for booty.

A Greek-owned freighter, the MV Irene, was taken in the Gulf of Aden with more than 20 crew yesterday. Pirates in as many as four speedboats seized the MV Sea Horse, a 5,000-tonne cargo ship flying the Togolese flag, soon afterwards.

The Greek Merchant Marine Ministry said that the Irene’s 22 crew were Filipinos. The East African Seafarers’ Assistance Programme, which tracks piracy, said they were all unharmed. In a separate incident a pirate gang fired rifles and rocket-propelled grenades at the Safamarine Asia, a Liberian-flagged vessel, but it escaped.

Rashid Abdi Sheikh, a Somali analyst with the International Crisis Group in Nairobi, said that the attacks appeared to be part of a surge in activity rather than a co-ordinated response to the killings. Rhetoric or warships would have only a limited impact on the pirate menace, he said.

“We need more creative solutions. We need support for the Puntland authorities, in the region where most of the pirates are based, and the creation of a national coastguard as well as alternative forms of employment for young people,” he said.

There have been ten successful hijackings this month. The spike followed a spell of bad weather that had kept the pirates ashore.

Snipers on the USS Bainbridge, a destroyer, killed three pirates on Sunday during an operation to free Richard Phillips, the captain of the Maersk Alabama. He had been held for five days on a lifeboat in the Indian Ocean after handing himself over to a gang of four teenage pirates to secure the safety of his crew.

Commander Frank Castellano, of the USS Bainbridge, revealed yesterday: “I can tell you throughout the entire event there were threats against his life. There had been times of rising tension where they had verbally said it was their intention to kill him.” He added that it seemed “to be inevitable that that was their intention”.

Captain Phillips is expected to be reunited with his crew today in the Kenyan port of Mombasa while the US authorities try to decide what to do with the gunman in custody.

The episode focused world attention on Somalia’s modern-day brigands, who have terrorised shipping since the mid-1990s. “I want to be very clear that we are resolved to halt the rise of piracy in that region,” Mr Obama said on Monday. “To achieve that goal we’re going to have to continue to work with our partners to prevent future attacks.”

Even as he was speaking, the pirates — armed with Kalashnikovs, rocket-propelled grenades and equipped with grappling hooks and ladders — were at sea in their fast-moving skiffs, speeding towards their latest victims.

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