British Prime Minister Gordon Brown opened a summit of some of the world's key decision makers Saturday and began by focusing on the jittery world economy. At the summit, which drew leaders from around the world and included former US President Bill Clinton, Brown said the current crisis in the world economy was the largest challenge of its type in modern times. “(It) is the biggest global economic restructuring I think we've seen since the industrial revolution,” said Brown. “So the world is a world of change.” The world economy has been in a state of gloom since credit markets froze on fears of bad lending in the US mortgage markets and International Monetary Fund chief Dominique Strauss-Kahn said conditions were unlikely to improve soon. “The forecasts we are going to release in a few days are not really improving,” Strauss-Kahn told those attending the summit at an exclusive country club on the outskirts of London. “Most of the downside risks identified six months ago have materialized.” He predicted a global growth rate of 3.7 percent - describing it as one of the lowest levels in the past two decades. Strauss-Kahn said ongoing difficulties in the US financial and labor markets continued to seep into other economies. Much of the blame for the economic malaise has been blamed on reckless behavior by global financiers whose dealings are often obscured by opaque work practices. “The need to have more transparency is obvious, correct and urgent,” Clinton said. Clinton said he had arrived at the summit fresh from campaigning for his wife Hillary Clinton's presidential bid in North Carolina on Friday. He said he had to be careful because there were people trying to catch him saying embarrassing things to use against his wife. “Every time I go anywhere, somebody representing her opponent will follow me around and try to ask me an embarrassing question,” he said. Climate change, international development and reform of international institutions are also on the conference agenda. Brown has taken every opportunity of late to call for reforms of institutions such as the United Nations, International Monetary Fund and the World Bank, saying unless structural changes are made the future of the organizations was at risk. On the sides of the summit Brown is to hold talks with South African President Thabo Mbeki to discuss ongoing concerns over elections in neighboring Zimbabwe, Brown's Downing Street office said Saturday. He has already held talks about the issue with the leaders of Ghana and Liberia who are also at the summit. As the former colonial power in Zimbabwe, Britain has been cautious about not taking a lead in events in Zimbabwe, fearing that such sentiment would play into the hands of Robert Mugabe who has long taken a strong anti-British stance. Others at the summit included recently elected Australian Prime Minister Kevin Rudd and New Zealand premier Helen Clark. __