Asia's factory activity expanded steadily in May on stockpiling by some companies to get ahead of supply shocks from the Middle East conflict, private surveys showed on Monday, a sign that the war's economic fallout is broadening across the region. The surveys came after the heads of the International Energy Agency, International Monetary Fund, World Bank and World Trade Organization warned the war in the Middle East was straining global energy supplies and hitting vulnerable economies hardest. Factory activity expanded in most Asian economies. China's private sector gauge grew for a sixth straight month and South Korea's hit the fastest pace in five years, highlighting a region-wide push to build buffers against potential conflict-led disruptions.