JERICHO, West Bank (Reuters) - Chief Palestinian negotiator Saeb Erekat was taken by ambulance to a hospital in Israel on Sunday for treatment of a worsening case of COVID-19, the Palestine Liberation Organization said. Witnesses said Erekat, 65, was on a stretcher when he was placed inside an Israeli ambulance outside his home in Jericho, in the occupied West Bank. Erekat, who is also secretary-general of the PLO, disclosed on Oct. 8 that he had contracted coronavirus. He was rushed to Jerusalem’s Hadassah Medical Center. A hospital spokeswoman said Erekat was in a serious but stable condition. He needed high-flow oxygen support and was being treated in an intensive care ward for coronavirus patients. There is heightened concern over Erekat’s vulnerability to the illness because he underwent a lung transplant in the United States in 2017. “Following his contraction of COVID-19, and due to the chronic health problems he faces in the respiratory system, Dr. Erekat’s condition now requires medical attention in a hospital,” the PLO’s Negotiations Affairs Department said in a statement. A member of Fatah, the most powerful faction within the PLO, Erekat has been one of the most high-profile faces of the Palestinian leadership for decades, especially to international audiences. Erekat is one of the most senior advisers to Palestinian President Mahmoud Abbas, and also served in top positions under Abbas’ predecessor, Yasser Arafat. His negotiating days date back to the earliest public negotiations with Israel in 1991 at the Madrid Conference during the presidency of George H.W. Bush, when Erekat was part of the PLO team. A proponent of a two-state solution of the Israeli-Palestinian conflict, Erekat has been a leading Palestinian voice in opposing Israel’s settlement policy in territory it captured in the 1967 Middle East war.