WTO chief Pascal Lamy on Sunday told EU participants to sort out first who will argue for what at June's G20 summit in Toronto, otherwise 'nobody' will listen. 'The frank reality is that it does not make sense,' the former EU trade commissioner said of seven European Union seats at the summit, after the bloc's new president Herman Van Rompuy also secured his ticket at last week's EU summit. 'If one European takes the floor, and then another European... nobody listens,' the World Trade Organization boss told a Brussels conference. He said the 'right solution, if I may, is to at least make sure they speak with one mouth -- not one voice -- on each topic on the agenda.' Lamy, who occupies the WTO's own seat in the G20, said he was 'sure that's what Van Rompuy is trying to get to,' but warned that 'if it doesn't translate into one mouth, it doesn't work.' Britain, France, Germany and Italy are each members of the Group of 20 major and developing economies seen as the forum for deciding how the world acts to avert repeat economic crises. Spain will also attend the Toronto summit, where leaders will try to agree how to regulate the finance industry and examine ideas such as whether a global levy on financial transactions could deliver insurance against future recessions. The European Commission meanwhile has a seat in the name of the 27-nation EU, which is a member in its own right, and now Van Rompuy has managed to obtain a place at the top table as well as the bloc's appointed chair. The issue of how much weight Europe's collective voice should be given has stirred debate among countries struggling to be heard at G20 level, although national interests often collide with EU perspectives, for instance where Britain's financial sector is concerned. Robert Hormats, US under-secretary of state for economic, energy and agricultural affairs, while stressing that representation was for the Europeans to sort out themselves, nevertheless gave his opinion that on trade matters, saying Europe is 'more effective' because it 'does speak with one voice'. 