Palestinian Prisoner Society lawyer Jawad Boulos told Ma’an that Issawi stopped taking supplements on Thursday to protest dissatisfaction with ongoing negotiations with Israel about his release.
There has been no positive progress in talks with Israel so far, Boulos added.
PA minister of prisoners Issa Qaraqe on Sunday condemned Israel for its “immoral attempts to blackmail and pressure Issawi,” saying negotiations carried out by Israel were a waste of time.
Issawi’s heartbeat has slowed down and he now weighs only 45 kg, Boulos added.
Israeli negotiators have been visiting Issawi at Kaplan Medical Center and pressuring him to accept proposals to end his hunger strike, Boulos said last week.
Issawi has been on hunger strike for over 265 days and has so far refused all offers by Israel to be exiled, insisting on being released to his home in Jerusalem.
Issawi, 33, was first arrested in 2002 and sentenced to 26 years for military activities on behalf of the Democratic Front for the Liberation of Palestine.
He was released by Israel under a prisoner swap deal in October 2011, but rearrested last July for violating the terms of the agreement by traveling to the West Bank from east Jerusalem.