The European Union will 'explode' if half its powers are not returned to individual member states, according to former French president Nicolas Sarkozy.The 59-year-old called for wide-scale reform of a system which is widely unpopular in countries including Britain. Mr Sarkozy, who lost the 2012 presidential election but who wants to stand again to become head of state in 2017, made his comments during a campaign rally in Mulhouse, eastern France. "Europe must give back 50 per cent of its responsibilities to member states," he said. "If not, the system is going to explode." Mr Sarkozy wants EU powers to deal only with specific areas including industry, agriculture, and trade. He is particularly concerned about the open borders policy in the EU, which assists illegal immigration. Referring to the Schengen agreement, which allows open frontiers among 26 European states, Mr Sarkozy said: "I no longer believe in the possibility of changing things in Europe from the inside. On Schengen, the situation can no longer continue." Referring to President Charles de Gaulle effectively boycotting Europe in 1965 over policy disagreements, Mr Sarkozy said: "We must carry out the empty chair policy."Mr Sarkozy said at another rally in Paris: "We cannot better integrate the immigrants who are here if we do not control the arrivals." But unlike British Prime Minister David Cameron, Mr Sarkozy does not want to challenge the free movement of EU citizens, saying: "This is a fundamental right of all Europeans. But it is a right for Europeans, not people from the whole world." Mr Sarkozy said he would not deal with Brussels again until his demands for frontier reforms were met. He pointed to France and Germany providing more than half of the economic output of the 18 nation Eurozone, saying that a Franco-German economic bloc should be in control of the single currency. Mr Sarkozy is keen to impress far-right National Front voters in France who are attracted by anti-Europe and anti-Immigration policies. He is likely to win the leadership of his party, the UMP, later this year, and will then go on to challenge his detested Socialist rival, President Francois Hollande, for power. However, Mr Sarkozy is also facing at least six corruption enquiries, which could make his return to the Elysee Palace an impossibility.