The Palestinian Prisoners Society said in a statement that 1,300 Palestinian detainees held under the notorious Israeli administrative detention started the hunger strike to voice solidarity with al-Fasfous, who has been on hunger strike for 63 days.
The Israeli policy of administrative detention allows authorities to extend the detention of a Palestinian prisoner indefinitely without charge or trial.
According to the NGO statement, al-Fasfous has entered a difficult health situation after more than 60 days of hunger strike to protest his administrative detention.
Al-Fasfous, 34, from the Dura town, southwestern Hebron, was detained by the Israeli forces in May, and was placed under administrative detention without charge or trial, prompting him to start a hunger strike against his detention.
According to the latest figures, nearly 5,200 Palestinians are languishing in Israeli jails, including 38 women, 170 minors and more than 1,200 placed under the administrative detention.