Somali pirates were engaged in a deadly stand-off with Spanish forces last night after threatening to kill three fishermen held hostage for more than a month.

The pirates, who seized the Spanish tuna trawler Alakrana, moved three hostages ashore from the boat off the Somali coast and threatened to kill them if the Spanish Government refused to release two captured pirates.

The pirates’ tactics mirror those being used to pressure Britain into negotiating the release of Paul and Rachel Chandler, who were captured last month aboard their yacht Lynn Rival. The couple were moved to the Somali mainland and latest reports suggested that they were being held in Bahdo, a town 125 miles northeast of the pirate haven of Haradheere.

Families of the crew of the tuna trawler urged Madrid to negotiate and release the pirates, who are being held in Spain.

Ricardo Blach, the captain of the Alakrana and one of the 36 hostages, said in a phone call to relatives that the pirates would kill the three hostages if their demands were not met.

“They have just told us that if in three days there is no change over the two held in Spain, they will kill the three and then three others and then more,” he said.

Silvia Albés, the wife of Pablo Costas, one of the hostages, said that he was very frightened: “My husband was crying. There came a point when all he could say was, ‘I love you, I love you, I love you. Please get me off the ship’.” Pirates on the Alakrana have fired a rocket-propelled grenade into the water and machinegun bullets into the air to ward off a Spanish frigate shadowing them.

The families of the trawlermen, from Bermeo in the Basque Country of northern Spain, pressed the Spanish Government to “act immediately” and “do everything possible to bring home the 36 fishermen”. The pirates are demanding $4 million (£2.5 million) ransom and the release of their two comrades, who face a series of charges, including 36 counts of kidnapping. Spanish troops captured the men when they left the Alakrana on a skiff two days after the hijacking on October 2.

Constantino Méndez, the Spanish Secretary of State for Defence, insisted that the release of the two pirates was “not negotiable”. He said that the pirates were dramatising the situation as a “negotiating tactic”.

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