Pirates operating off the coast of Somalia have begun to use aggressive new tactics including torture against captives, according to the commander of the European Union naval force.
Captured sailors now face being thrown overboard or used as human shields, locked in freezers or having plastic ties put on their genitals in the mounting battle between international forces and Somali pirates.
"There have been regular manifestations of systematic torture," Royal Marines Commandant General Buster Howes told a press agency.
"If warships approached a pirated ship too closely, the pirates would drag hostages on deck and beat them until the warship went away."
The restraint of earlier years has been replaced lately with "a willingness to use violence much more quickly and much more violence."
Until now the consequences of the surge in piracy off the Horn of Africa have been largely commercial with most ransomed captives speaking of reasonable treatment by the gangs.
The claims from EU naval force suggest that Somali fishermen responding to illegal fishing in their waters made up the bulk of the initial pirate forces, but have now been succeeded by more brutal gangs intent on quicker returns from hijackings.
The new developments come after a recent hardening in tactics used against pirates. South Korean forces last month killed eight Somalis and captured five more while storming a hijacked cargo ship, releasing all the hostages. The US navy and French forces have previously killed Somalis in similar operations.
Over the past three years an unprecedented multinational armada has been assembled in the waters from the Gulf of Aden to the Indian Ocean aimed at protecting commercial shipping routes. Despite this, Somali pirate gangs, using often ramshackle equipment and basic skiffs with outboard engines, have been able to hijack vastly larger craft including oil-laden supertankers.
There are 47 vessels and more than 800 seamen being held hostage off Somalia, according to independent maritime monitors Ecoterra. EU and International Maritime Bureau estimates are lower but still register a surging problem. Eleven captured vessels are said to be deployed as "mother ships" for further raids, the EU naval force claims.
The crisis has prompted a gradual escalation of defence tactics with merchant ships deploying high pressure water hoses, audio deterrents and other non-deadly equipment to fend off buccaneers. The tuna fleet based in the Seychelles now sails with Spanish and French marines aboard for protection and other fishing fleets have deployed armed agents including Somalis.
The EU commander said new tactics were being used to bypass ships' defences including attacks on so-called "citadels" – safe rooms on board where the crew can lock themselves away. These are being attacked with grenades and rocket launchers. Last week a three-day siege of crew members on the German-flagged MV Beluga Nomination ended with the attackers getting in and executing one of the sailors.
Some analysts remain sceptical of the torture reports amid fears that it may be used to justify a stronger military response to piracy.
Roger Middleton, a Somalia expert with the London-based think tank Chatham House said: "Until now the experience has certainly been unpleasant with some captives beaten, pushed around or denied adequate food but nothing to suggest torture is being used."
The EU commander's torture claims are based on intelligence reports and debriefings from released sailors.
Somalia has been without a central government since 1991 when the regime of dictator Siad Barre was overthrown.