By Jan Strupczewski BRUSSELS (Reuters) - European Union leaders have postponed a deeper discussion of the future of the euro zone until December because of divergent views in the biggest countries and because of the more pressing migration issue, diplomats said. EU leaders, who meet on Thursday in Brussels, were to talk about fleshing out a report on the future of the Economic and Monetary Union (EMU) prepared by the 28-nation bloc's top five officials in June -- the so-called five presidents' report -- as the Greek debt crisis was shaking the euro zone's foundations. Officials said that while both Germany and France wanted a stronger euro zone, the Germans were more focussed on how to enforce existing EU rules while the French are more focussed on how to distribute money from a future euro zone budget, called a "fiscal capacity".