An assailant ambushed and stabbed an Israeli policeman in the back Sunday near a church in the walled Old City marking the legendary burial place of Jesus, police said. The officer, identified as Moshe Tadji, 24, was in moderate condition at Jerusalem's Hadassah Hospital with a punctured lung after undergoing surgery to remove the knife, a hospital spokeswoman said. Police shut the city's stone-walled gates after the 11:00 a.m. attack for an hour and detained dozens of Palestinians in the area for questioning. The assault came on a day designated by Palestinian underground leaders in a leaflet for ``distinguished escalation'' as part of the 31-month-old uprising against Israel. Police Minister Roni Milo of the right-wing Likud bloc rushed to the scene from the weekly Cabinet session and vowed police would use tougher measures to prevent further attacks. ``We see this attack in a very grave light,'' Milo said on Israel radio. ``There are new methods of action that will be carried out as soon as possible,'' he added, without elaborating. Police and witnesses said Tadji, who routinely works in Jerusalem's square-mile old city, was ambushed by a youth with black curly hair and wearing blue jeans and a yellow shirt, outside the Holy Sepulcher church in the Christian Quarter. The church is held by Catholics to be the burial site of Jesus. Protestants believe the burial place is outside the walled city in a shrine called the ``Garden Tomb.'' Doctors later said they removed an 8-inch-long kitchen knife from Tadji's back and that he was in moderate condition, Hadassah spokeswoman Yael Bossem said. The area of the Holy Sepulcher has been a source of Arab-Jewish tensions following the settlement established by a group of armed Israelis in a nearby building in April. The Supreme Court later ordered most settlers evicted after strong protests from the United States, but allowed about 20 to remain pending resolution of a tenancy dispute in the building. Israel captured East Jerusalem, with the West Bank and Gaza Strip, in the 1967 Middle East war. Jerusalem was annexed shortly afterward. The city is home to more than 350,000 Jews and about 140,000 Palestinians. During the uprising, 723 Palestinians have been killed by Israelis and 45 Israelis have been slain by Arabs. Another 232 Palestinians have been killed by fellow Arabs as alleged collaborators with Israel. Also Sunday, Israel reopened a Palestinian vocational college in Abu Dis in the West Bank as part of a plan to reopen colleges shut during the uprising to prevent unrest.