RAMALLAH, West Bank - Palestinian Authority President Mahmoud Abbas, who officials said is being treated for a lung infection, will remain in hospital for an eighth day on Sunday.The 82-year-old leader had been expected to be released from hospital in the West Bank on Sunday, but this was postponed, Abbas' office said in a text message to journalists.Abbas, who is a heavy smoker, was admitted on May 20 for what doctors had initially said were medical tests following ear surgery. He was shown on Palestinian television last week walking along a hospital corridor and sitting in an armchair reading a newspaper.A Palestinian official, who spoke on condition of anonymity, said Abbas was still undergoing treatment and would not be released on Sunday, adding that he has been holding meetings with international and Palestinian officials at his bedside.The official Palestinian news agency Wafa ran a statement which quoted Istishari Hospital's medical director, Said Sarahneh, as saying test results show an improvement in his health."President Mahmoud Abbas's condition is showing a continuous and speedy improvement," Sarahneh told Wafa.Abbas, who was also hospitalized for medical checks during a trip to address the UN Security Council in February, became president after the death in 2004 of Yasser Arafat.The Western-backed president pursued US-led peace talks with Israel but these broke down in 2014 and his democratic mandate expired eight years ago.There has been no presidential election since 2005 and the term of office is only five years. His authority is essentially limited to the Israeli-occupied West Bank, with the Islamist group Hamas in control of the Gaza Strip.Abbas has no formal deputy in the Palestinian Authority. In theory, the speaker of parliament would take over on an interim basis if the president were to die in office.But the speaker's role is held by a Hamas representative, and Abbas’s Fatah faction would likely dispute the constitutional legitimacy of his taking over.