Somali pirates hijacked an Italian-owned bulk carrier on Thursday about 350 miles (560 km) off the coast of Oman, the European Union's anti-piracy taskforce and the vessel operator said.

EU Navfor said the 74,500 tonne MV Rosalia D'Amato was on its way to Bandar Imam Khomeini in Iran from Brazil with a cargo of soya when an armed pirate gang onboard a single skiff attacked.

"Coalition warships had communications with the vessel and were told: 'pirates onboard stay away'," the EU force said in a statement.

Without citing its sources, Italian news agency ANSA said the vessel was now heading to the coast of Somalia.

Pirates from the lawless Horn of Africa nation continue to outwit an international flotilla of warships patrolling the busy water routes that link Europe with Africa and Asia.

Typically the pirates anchor the vessels off their land base until a ransom is paid, at which point the vessel along with its crew and cargo is released.

An official at Perseveranza, the Naples-based operators of the vessel, said they had been in contact with the hostage crew of six Italians and 15 Filipinos and all were well.

In February, pirates seized an Italian oil tanker in the Indian Ocean, some 800 miles off the coast of Somalia.

Separately, pirates said a botched sea and airborne attempt to rescue several Iranian hostages held in Hobyo, a pirate base along the coast of central Somalia, left three pirates and one Iranian seaman dead.

"They launched two small boats and a helicopter against us. We had no other option but to fight with them," a pirate who identified himself as Hussein told Reuters by telephone.

"From our side, three were killed and four were wounded and I can confirm that one of the Iranian hostages died," he said.

It was not clear which nation's navy had carried out the rescue attempt, which failed to free any of the hostages. Local residents confirmed the attempted raid. – Reuters