 UN Secretary-General Ban Ki-moon warned on Friday that the global economic crisis could lead to a political crisis and social unrest and called on the world's leading economies to act. "I am concerned that if we do not properly address this issue swiftly, this may develop rather alarmingly into political instability, into a political crisis," the U.N. chief told diplomats in Moscow. Ban, who was speaking less than a week before he attends a crisis meeting of leaders of the G20 group of industrialised and developing nations in London, spoke of the impact of the economic crisis on Russia and Eastern Europe. Latvia's government collapsed last month after a wave of protests, while Greece, Bulgaria and Lithuania have seen popular anger explode into riots. "Looking around the world we see a growing list of political instability. If we do not manage it properly, this crisis, I am concerned that this crisis may develop into global political instability," he said. "If life goes much like this and harder ... social unrest will surely increase," he said. "That is why in London I will speak out forcefully for action to prevent the potential catastrophe in human development." The head of the International Monetary Fund, Dominique Strauss-Kahn, on Monday said the crisis would push millions into poverty and unemployment, risking social unrest and even war. Ban used his Moscow speech to call on countries to use anti-crisis stimulus packages to help fight climate change. "My answer is it would be very smart to invest a certain proportion of this stimulus package in green growth and by doing this we can catch two birds with one stone," he said. "If we are going to spend trillions of dollars on the global stimulus packages let us be smart and tackle climate change at the same time." 