They urged Spanish authorities to release two suspected Somali pirates who were captured and brought to Spain over their alleged role in the seizure of the boat and its 36-member crew, as demanded by the kidnappers.

The Spanish government has ruled out freeing the two suspects but did not rule out transferring them to the court system of an African country, like Kenya, as happened in a similar case in May.

"That is an issue for the courts to decide," Deputy Prime Minister Maria Teresa Fernandez de la Vega told reporters after a weekly cabinet meeting, adding it was "risky" to talk about this "technical topic which is legally very complicated."

Three crew members who had that had been removed from the trawler on Thursday in what was seen by the Spanish government as a bid to add pressure on Madrid to give in to the pirates' demands were returned to the vessel on Friday, Spanish Foreign Minister Miguel Angel Moratinos said.

"What does this mean? It means we must remain calm. Kidnappings are complicated situations, with highs and lows, they are very difficult and stressful. But we must remain confident and calm," he told a news conference.

"If we remain clam and confident I am certain that what all Spaniards what, what the families want, what the government wants - that the hostages can return to their homes safe and sound and this kidnapping ends satisfactorily."

Ricardo Blach, the skipper of the boat, the Alakrana, and one of the 36 hostages, told Spanish media on Thursday that the pirates had threatened to kill three of them in three days unless their demands were met.

The pirates, who seized the boat on Oct. 2, are demanding four million U.S. dollars ransom as well as the release of the two suspected pirates.

The crew are enduring difficult conditions with "little drinking water or food," Argi Galbarriatu, the sister of one of the crew members, told a news conference in the port of Bermeo, in Spain's northern Basque region, where the Alakrana is based.

In addition to the 16 Spaniards, the crew includes eight Indonesians as well as others from Ghana, the Ivory Coast, Madagascar, Senegal and the Seychelles. In a joint statement, the families urged Spanish authorities to "act immediately" and "do everything possible to bring home the 36 fishermen."

"We demand that all the parties work in the same direction" and that the Spanish government opts for "negotiation" rather than putting the life of the crew in danger with military action, said Maria Angeles Jimenez, the wife of another of the crew.

Spanish troops monitoring the area off the Somali coast captured the two suspects shortly after they left the Alakrana on a small boat. Earlier on Friday Spain's secretary of state for defense, Constantino Mendez, reaffirmed that the two suspects would not be released, and "that is not negotiable."

He told Spanish National Radio that the crew are "in good health" and that the pirates are "dramatising" the situation in a "negotiating tactic." Two Spanish frigates remain on watch off Somalia.