An Eta prisoner on hunger strike has ripped out his feeding tube, sparking fears that he is close to death after 112 days without eating.

The Spanish prison service said that Iñaki de Juana Chaos, the Basque separatist leader convicted of killing 25 people, mainly soldiers and policemen, in the 1980s, had received no nutrients since Friday. A lawyer who spoke to de Juana said that he had pulled out the tube keeping him alive, apparently furious with media reports that he had abandoned his protest.

The case has exposed the deep divisions within Spain and placed the Socialist Government in an excruciating dilemma. More than 75,000 people rallied in Madrid on Saturday, calling on the Government not to free de Juana despite a recent Supreme Court judgment making him eligible for parole.

Crowds called José Luis RodrÍguez Zapatero, the Prime Minister, a traitor for having attempted to negotiate a peace deal with Eta before the group planted a bomb at Madrid airport on December 30, killing two people. The opposition Popular Party vowed to fight any decision to free de Juana.

Still, the Government’s allies seemed to be preparing Spaniards for the possibility that such a notorious killer could soon walk free. Juan Carlos RodrÍguez Ibarra, a regional Socialist Party baron from Extremadura, appealed to the Interior Minister “not to let that swine become a hero after his disgusting and repugnant life” by dying in prison. “Do not let that bastard die,” he said.

De Juana was on the verge of release two years ago after completing an 18-year sentence for a series of attacks in the 1980s. Fearing a public outcry, the Government charged him with making veiled terrorist threats in two newspaper articles that he wrote from prison. A court gave him another 12 years and seven months, prompting him to begin his hunger strike on November 7.

To keep him from dying while on remand, the courts ordered de Juana to be force-fed on December 12. A tube was inserted through his nose into his stomach and he was strapped to his bed during the 12-hour feeding sessions.

Now the Government must decide whether to tie him down 24 hours a day to prevent him from ripping out the tube. Doctors fear that a violent struggle could trigger a heart attack in his weakened condition, so they have also received permission to sedate him. But they know that they cannot keep him alive this way indefinitely.

The Government could free de Juana on parole under a recent court ruling that reduced his new sentence from 12 years to three. Such a decision would prompt uproar among victims’ groups, the largest of which is allied to the conservative Opposition. Letting him die could hand Eta a martyr and trigger a new cycle of violence in a conflict that appeared to be heading for extinction.

Dozens of people were injured in the Basque Country this weekend when riot police broke up a march in support of de Juana. A Basque leader was arrested and later released.

Eta’s politicial allies have been calling for a resumption of the peace process and hinted that they could give ground on several longstanding demands. But the Popular Party called the conciliatory words from Basque separatists a trap, and has vowed to oppose any effort by Mr Zapatero to revive talks.

Alfredo Pérez Rubalcaba, the Interior Minister, said that the Opposition had used the issue in a disgraceful manner, “setting back the end of terrorism and breaking the unity of democrats” in the antiterrorist fight.

Eta has killed more than 800 people in its campaign for an independent Basque homeland in northern Spain and southern France. It is listed as a terrorist group by the US and the EU.

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