Khader Adnan, a prominent Palestinian prisoner who had been on a hunger strike in an Israeli prison for 87 days to protest his detention, died early Tuesday, according to his lawyer and Palestinian and Israeli officials, amid rising violence in the occupied West Bank.
Palestinian leaders and armed groups vowed retaliation, saying Israel was responsible for the death of Mr. Adnan, the first Palestinian prisoner to die on a hunger strike since 1992.
A barrage of more than 20 rockets was launched into southern Israel from the Gaza Strip on Tuesday afternoon, seriously injuring a Chinese construction worker in the town of Sderot, according to Israeli media.
A joint statement from armed Palestinian groups in Gaza claimed responsibility for the rockets “as a first response to this heinous crime that will trigger responses from our people in all arenas and places of engagement.”
Islamic Jihad identified him as a longtime leader, and called for retaliation against Israel. Hamas, another armed group, also vowed retaliation.
Israel fired tank shells at border observation points inside Gaza. There were no injuries.
The Palestinian Foreign Ministry also said it held Israel responsible for Mr. Adnan’s death, called for an international investigation and said it planned to refer the matter to the International Criminal Court. The Palestinian prime minister, Mohammad Shtayyeh, accused Israel of “a deliberate assassination,” by failing to release Mr. Adnan and give him proper treatment.
Mr. Adnan, 44, was arrested by Israel on Feb. 5 on suspicion of membership in a terrorist organization, support for terrorism and incitement as a member of the Palestinian armed group Islamic Jihad. He had been on a hunger strike since his arrest.
Mr. Adnan was being held at the Israel Prison Service medical center when he was found unconscious in his cell on Tuesday, prison authorities said. He was given cardiopulmonary resuscitation and then transferred to a hospital, where he was pronounced dead.
In a statement on Monday, Physicians for Human Rights Israel, a nongovernmental group of doctors that examined Mr. Adnan, had warned that his death was “imminent” and called for him to be transferred to a hospital. But an appeals court had ruled that there was no evidence that Mr. Adnan was in an urgent medical state.
Hana Herbst, a spokeswoman for the Israel Prison Service, said Mr. Adnan had been taken to a hospital on numerous occasions, but had each time refused medical treatment and was transferred back to the Israeli prison medical center.
“He decided to go on hunger strike and he refused any medical examination and any medical treatment,” Ms. Herbst said. “We couldn’t have done anything different other than forcing him to take medical treatment, which we can’t do.”
The doctors group, though, said in the statement that Mr. Adnan wanted to be hospitalized and gave three conditions for undergoing medical examinations, which included allowing his family to visit, being accompanied by a doctor from the rights group and that his medical information would not be shared with the Israeli prison service.
At Mr. Adnan’s last court hearing on Thursday, which he attended remotely from his bed, the military judge denied a third appeal for his pretrial release, which cited his deteriorating medical condition, according to court documents.
In his rejection of the appeal, a military judge, Lt. Col. Menachem Lieberman, said Mr. Adnan “fully understands his actions and where they will lead him. He is the master of his own body.”
Mr. Lieberman said he had not been presented with any medical opinion that Mr. Adnan’s life was in immediate danger, according to the court documents.
Dr. Lina Qasem-Hassan, a family medicine specialist and the chairwoman of the doctors group, visited Mr. Adnan on April 23 and said he struggled to move and maintain a basic conversation. His limbs had atrophied and he was dangerously emaciated, weighing less than 125 pounds, according to her assessment, the group said in its statement.
The doctors group said in its statement that it had been urging his transfer to a hospital based on urgent medical grounds for weeks.
“According to medical ethics principles, Adnan’s requests are reasonable,” Anat Litvin, the director of the group’s prisoners and detainees department, said in the statement on Monday. “There is no reason to deny them other than a desire to punish him and end his strike. This is a clear power struggle between the security authorities and the hunger striker.”
Mr. Adnan, a baker and a married father of nine who lived in the town of Arraba in the Israeli-occupied West Bank, had been imprisoned by Israel 10 times, often under administrative detention. He had also been imprisoned at least twice by the Palestinian Authority, including in 2000, when he undertook his first hunger strike.
In an interview with The New York Times last year, Mr. Adnan described hunger strikes as a crucial weapon in resisting Israeli occupation. He had helped pioneer the practice of individual hunger strikes by Palestinian prisoners, conducting a 66-day strike in 2011 that inspired others to use it as a means of protesting Israel’s incarceration of Palestinians, especially the practice of administrative detention, which Israel uses to indefinitely detain people without charges or trials, based on secret evidence.
Over his many hunger strikes, Mr. Adnan had settled on an approach that he said in the interview with The Times was aimed at exerting maximum pressure on Israel and demonstrating his full commitment to seeing the strike to the end, including refusing to take supplements or sugar water. He said he considered that allowing medical exams indicated a prisoner’s fear for his life and reluctance in carrying out the hunger strike.
“It is not an easy act, maybe the prisoner will survive and maybe the prisoner won’t survive,” he said. “We’re not entering the hunger strike in order to be martyred, but we are willing to be martyred if it happens.”
Hiba Yazbek contributed reporting from Jerusalem, and Gabby Sobelman from Rehovot, Israel and Ameera Harouda from Gaza City.
