Inaugurating this year's Hanover Fair, German President Horst Koehler spoke out Sunday against protectionism and called for an "ecological industrial revolution" worldwide, according to dpa. He was speaking at the official opening ceremonies before the five-day fair opens its doors to the public on Monday morning. The expo is rated by many as the world's top trade fair for factory machinery and parts including robots. Koehler, the German head of state, and a former head of the International Monetary Fund, said world trade looked set to shrink in 2009 by the biggest margin since the Second World War. Criticizing recent calls for protectionism in some countries, he demanded a "clear-cut timetable" to conclude the lagging Doha trade round of world talks on encouraging free trade. Visiting South Korean Prime Minister Han Seung-Soo agreed, telling fair guests in Hanover, "The more difficult the crisis, the stricter we should be about the liberalization of foreign trade. Increasing trade barriers only causes a vicious circle of protectionism." Han also backed Koehler's call for what he called "green growth." Koehler said the whole world economy had to become more environmentally friendly. He said, "We'll best achieve that by respecting the fundamentals of market economics while keeping in mind the fair distribution of wealth." South Korea is the "partner nation" at the fair this year and hopes to expand its manufacturers' sales on the European market. Seoul has flown the National Dance Company of Korea, the Yepoong drummer band and the Kaya-Go traditional Korean music ensemble to Hanover to perform for VIP invitees and interested German audiences. The fair bills itself as 13 specialist fairs rolled into one, with sections devoted to fields such as industrial automation, pumps, power-generation machinery and paints. The organizing company, Deutsche Messe, said it booked 6,150 exhibitors from 61 nations.