The European Union's anti-piracy force yesterday attacked pirate bases along the Somali coast for the first time, using helicopters to destroy suspect boats.

Stepping up efforts against a multimillion-dollar criminal enterprise that international navies have struggled to contain, the EU Naval Force (EU Navfor) said it had conducted an overnight attack on pirate targets.

It is the first time the EU has taken its fight against the pirates to Somali soil since its mandate was expanded in March to allow strikes on land, as well as at sea.

A Somali pirate, who identified himself as Abdi, said a helicopter attacked the central Somali coastline near Hardhere, a known pirate haven.

He claimed: "An unidentified helicopter destroyed five of our hunting boats early in the morning. There were no casualties. We were setting off from the shore when the helicopter attacked us. We ran away without counter-attacking."

EU Navfor said it carried out the attack to destroy pirate equipment, four days after Somali gunmen hijacked a Greek-owned oil tanker, carrying close to one million barrels of crude oil, in the Arabian Sea.

EU Navfor's operation commander, Rear Admiral Duncan Potts, said the attack would "further increase the pressure on pirates and disrupt their efforts to get out to sea to attack merchant shipping and dhows".

Initial surveillance indicated no Somalis had been wounded as a result of the attack, a spokesman for EU Navfor said, adding: "We have monitored several locations, and the time and place chosen was one of the best opportunities."

He said the force would launch similar attacks in future "given that those targets will show up again".

The EU extended its counter-piracy operation off the coast of Somalia in March to the end of 2014, and expanded the area it covers to include the coastline.

Until yesterday, it had only operated in waters off Somalia.

The decision to extend operations to the Somali coastline, however, means EU Navfor can target weapons and other equipment stored onshore, in order to reduce the pirates' ability to launch attacks.

Despite successful efforts to stop attacks in the Gulf of Aden shipping lane, international navies have struggled to contain piracy in the Indian Ocean and Arabian Sea due to their limited resources and the vast distances involved.

A maritime analyst said: "It may take time to limit the overall scope of pirate activities. The pirates have had virtually unconstrained ability to operate for five or six years now, and that won't be rolled back rapidly."

The pirates have raked in millions of dollars in ransoms in recent years in what has become a highly organised, international criminal enterprise.

A study published earlier this year by the One Earth Future Foundation showed Somali piracy cost the world economy some $7 billion last year, with ransoms paid reaching a total of $160 million.

Somali pirates are switching back to using smaller cargo and fishing vessels as motherships, hoping to evade detection in the face of more robust maritime security.

There is a risk they may step up hostage-taking to discourage further military operations, said Rory Lamrock, an intelligence analyst with security firm AKE.

"The concern is that pirates will relocate logistics bases further inland, possibly among coastal communities, to avoid EU airborne attacks," he said.