Fifty Israeli armoured vehicles, including tanks, moved into a Palestinian refugee camp near the West Bank town of Nablus early Tuesday, Palestinian security sources said. There were exchanges of fire at the start of the Israeli operation which was backed up by two helicopter gunships, the sources added, giving no report of casualties. But later that day, residents from the Balata camp hurled stones at the troops. A 12-year-old boy was seriously wounded in the head by a rubber bullet, Palestinian medics said. They named him as Ahmed Ismail. Israeli troops seized four multi-storey buildings on the outskirts of the Balata camp in the northern West Bank and proceeded to carry out a house-to-house search with sniffer dogs, the sources said. The Israeli army said it was a routine operation to arrest Palestinian activists. **Bethlehem Bar on Arafat again*** Israel last night barred Palestinian leader Yasser Arafat from Christian celebrations in Bethlehem for a third straight year, as Egyptian mediators once more pressed reluctant Palestinian armed movements to halt attacks on Jewish state. With efforts to revive peace talks at a standstill, Israeli leaders sent a mixed message to the Palestinians: Israel is ready to negotiate but will take unilateral action if peace talks fail. Vice Prime Minister Ehud Olmert, who has advocated a unilateral pullout from occupied lands in recent weeks, warned the public to be ready for extremely painful concessions. He said "tens of thousands" of settlers in the West Bank and Gaza would be uprooted. Israel will co-ordinate any unilateral moves in the West Bank and Gaza with the US, its foreign minister said. In Gaza, the Egyptian delegation arrived for separate talks with Arafat's Fatah faction, Hamas and Islamic Jihad. **PHOTO CAPTION*** Ahmed Emran, a 15-year-old boy, left, screams as his twin brother Noor-Eddine, who was critically wounded in the head, is carried by a medical worker to an ambulance after being shot at the Balata refugee camp adjacent to the West Bank town of Nablus, Tuesday Dec. 16, 2003. (AP Photo/Nasser Ishtayeh)