More than 150 ETA prisoners were on hunger strike on Monday in an attempt to force through the release of Iosu Uribetxeberria Bolinaga, who is suffering from cancer.
The protests vary in gravity from life-threatening to purely symbolic; many ETA inmates said they would fast just for one day. Others are on a so-called patio strike, whereby they refuse to leave their cells.
Uribetxeberria was jailed for 32 years in 1998 for the kidnapping of prison director José Antonio Ortega Lara, who was held by the terrorist organization for 532 days.
The government has not altered its stance on Uribetxeberria's case, stating it will follow normal procedure and await the results of a biopsy before deciding whether to grant him compassionate release.