Yemen's Human Rights Minister Huriya Mashhoor said she began a hunger strike on Sunday to press authorities to release dozens of activists held since the 2011 uprising against former president Ali Abdullah Saleh.
"I am on hunger strike and I will not stop until the imprisoned revolt youths are released," Mashhoor told AFP. "Their only fault was that they participated in the peaceful revolt."
Activists say Mashhoor joined 20 other leading youth activists who went on hunger strike and a sit-in since Saturday at the central prison compound in Sanaa.
In total, 58 men who participated in protests that forced Saleh to step down in February 2012, remain incarcerated, while the fate of 17 others remains unknown, according to local rights group Hood.
The organisation said 20 detainees began a hunger strike on May 24, stepping up pressure to release them.
Leading youth activist Walid al-Ammari said that "we visited the detainees at the central prison yesterday (Saturday) and found their situation difficult and thus decided to begin a solidarity strike in the prison and will not leave without them."
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Ammari warned of "escalation" if the activists were not released.
A government source told AFP that President Abdrabuh Mansur Hadi had started consultations with the cabinet and his advisers to resolve the matter.
Last month, hundreds of Yemenis demanding the release of detainees staged a sit-in outside the office of the public prosecutor whom they hold responsible for keeping the inmates behind bars.
They had urged Hadi in a statement to "dismiss the public prosecutor and implement (his own) decision to free those detained during the revolution".
In March, Hadi issued a decree ordering the release of those detained during the revolution, and activists accuse the public prosector, a remnant from the Saleh era, of ignoring it.
Activists said some of the detainees are suspected of involvement in an attack on Saleh in June 2011 which killed 11 of his guards.
During the 2011 uprising, which erupted as part of the Arab Spring wave of protests, demonstrators frequently clashed with security forces and partisans of Saleh.
Hadi was elected in February 2012 as part of a UN-backed, Gulf-brokered exit deal that eased veteran Saleh out of office after 33 years in power, and ended a year of protests.