The European Central Bank's chief economist Otmar Issing need not automatically be replaced by a German when he retires from the bank's six-strong executive board next year, Luxembourg central bank chief Yves Mersch said on Monday. "Let's keep to the (Maastricht) Treaty. There's nothing automatic in the process. The EU treaty states that the best man for the job should be appointed," Mersch told the news agency DPA-AFX. Issing, who came to the ECB from the Bundesbank and is widely regarded as one of the most influential people on the executive board, is scheduled to retire in 2006. Although Germany is likely to want another German to replace him, smaller euro-zone countries argue it is their turn to have a seat on the board, which is responsible for the day-to-day running of the world's second most important central bank, after the US Federal Reserve. However, Mersch added that "as a Luxembourger, I'm a realist." And so far, the euro zone's three biggest economies, France, Germany and Italy, had always held a seat on the board. As head of Luxembourg's central bank, Mersch sits on the ECB's decision-making governing council, which is consulted when executive board members are appointed. But the final decision rests with the EU heads of government.