text: Hamas cleric jailed in Israel hospitalised briefly . JERUSALEM 1996-08-29 Israeli prison officials took jailed Islamic militant Hamas founder Sheikh Ahmed Yassin to hospital briefly on Thursday for medical tests , officials said . " This evening Sheikh Yassin completed medical checks and returned to Ramle prisons authority medical centre , " said a spokesman for Israel 's internal security ministry . A prison official said Yassin had a mild case of pneumonia . The 60-year-old Moslem cleric , jailed by Israel since 1989 , is serving a life sentence for ordering attacks by Hamas guerrillas against Israeli targets . The ailing Yassin is the spiritual leader of the fundamentalist Hamas group which has killed scores of Israelis in suicide attacks aimed at wrecking Israel-PLO peace deals . Palestinian President Yasser Arafat has demanded that Israel release Yassin -- who is confined to a wheelchair -- on humanitarian grounds . Israel said last month after it recovered the body of a soldier abducted by Hamas seven years ago that it would consider freeing Yassin .