British Prime Minister Gordon Brown and his predecessor, Tony Blair, made a rare public appearance together Thursday to kick off 24 hours of Middle East diplomacy aimed at spurring investment in the occupied territories. Brown opened the conference by calling for more private sector investment in the West Bank and Gaza Strip. He said such investment was vital for peace. "There is an economic prize before us," Brown said. "There is a real chance to build on the ingenuity and skills of the Palestinian people to build real peace and prosperity in the region." However, a meeting of ministers from the so-called Middle East Quartet of peacemakers will take place on the sidelines of the conference. UN Secretary-General Ban Ki-moon will chair that meeting and also meet with foreign ministers from a number of Arab states in an effort to develop economic institutions in the West Bank and Gaza.