"Fifty prisoners from different Palestinian factions -- including Hamas, Islamic Jihad, the Palestinian Front for the Liberation of Palestine (PFLP) and the Democratic Front for the Liberation of Palestine (DFLP) -- have joined the hunger strike," the National Committee to Support the Hunger Strike, which includes representatives of most Palestinian political factions, said in a Thursday statement.
Among the most prominent detainees to join the hunger strike were PFLP Secretary-General Ahmad Saadat; long-serving Palestinian prisoner Nael Barghouti; senior Hamas members Abbas al-Sayyed and Hasan Salama; and Islamic Jihad leader Zaid Bisisi.
Saadat's daughter, Somoud, told Anadolu Agency that, "despite my father's advanced age and poor health, he decided to join the 'battle of the empty stomachs' against Israel".
"The Israeli authorities are doing everything they can to break the will of the prisoners," she said. "Nevertheless, all the Palestinian factions have decided to carry through with the hunger strike until the end."
She went on to say that her father had rejected an Israeli offer to negotiate prisoners' demands in return for not joining the hunger strike.
Issa Qaraqe, head of the Palestine Liberation Organization's committee on detainees, told Anadolu Agency that the decision by Palestinian faction leaders to join the hunger strike constituted a step towards Palestinian national unity.
"This is a message to the Israeli authorities that the strikers have more surprises up their sleeve," he said.
Qaraqe went on to say that "dozens" more prisoners were expected to join the strike in the days ahead.
"Despite the repressive measures taken by the Israeli authorities against prisoners, the decision was taken not to retreat until all demands have been met," he said.
"Israel's prisons will see continued escalations in the upcoming period," he added.
Led by jailed politician Marwan Barghouti, more than 1,800 Palestinian prisoners began an open-ended hunger strike on April 17 to demand more prison visits, better medical care and improved treatment for female inmates.
According to Palestinian figures, Israel is currently holding more than 6,500 Palestinians -- including 57 women and 300 children -- at 24 detention centers throughout the country.