Madrid  - The fate of a suspected Somali pirate brought to Spain took a new twist Thursday when the estimate of his age was modified - for the third time.

Cabdiweli Cabdullahi, alias "Abdou Willy", was to be placed again under the authority of National Court judge Santiago Pedraz after having been handed over to a judge responsible for minors, judicial sources said.

A third medical report on Cabdullahi's age concluded that he was 18 years old, after a previous investigation said he could be younger. An initial report had concluded he was 19 years old.

The latest test results mean Cabdullahi can be jailed instead of being kept at a centre for minors.

That can only be done, however, with the approval of Pedraz, who was expected to seek a "definitive" medical report on the Somali's age.

Soraya Saenz de Santamaria of the opposition conservative People's Party (PP) accused the government of having brought Cabdullahi and a fellow suspect to Spain without knowing whether they could be tried there.

The daily El Mundo described Cabdullahi's judicial situation as a "mess."

Cabdullahi and his fellow suspect Raagegeesey Hassan Haji were flown on October 12 to Spain, where they were interrogated and remanded in custody.

The pair are suspected of participating in the hijacking of the Basque fishing vessel MS Alakrana on October 2. The trawler is currently being held off Somalia while Spanish negotiators are trying to obtain the release of its 36-member crew.

Two of the 13 suspected pirates were detained by a Spanish frigate participating in the European Union's anti-piracy Operation Atalanta when they left the Alakrana on board a skiff two days after the hijacking.

Prime Minister Jose Luis Rodriguez Zapatero's government came under increasing criticism over its handling of the case, with Saenz de Santamaria saying the drawn-out negotiations gave a "weak image" of the Spanish state.

All the Basque political parties were planning to attend a rally to press for the release of the 36 crew members of the Alakrana, who include 16 Spaniards, on Friday.

The government has been criticized for bringing the two detained suspects to Spain from Africa, where negotiators could have tried to trade their freedom against concessions from the pirates, who were believed to be seeking a large ransom.

The government has rejected a request from fishing companies to place marines on board fishing vessels to keep pirates at bay, arguing that would be illegal.

The defence ministry has, however, allowed the companies to hire private guards, and was due to inform them about the kinds of weapons that the guards could carry. The companies want them to have machine guns and assault rifles.

Some Seychelles-flagged Spanish fishing vessels already have British former soldiers on board, according to the daily El Pais.(dpa)