Berlin, May 31, 2010, SPA -- German Chancellor Angela Merkel was dealt a further blow today, as President Horst Koehler unexpectedly resigned after coming under attack for comments he made about Germany's military role in Afghanistan, according to dpa. After visiting the region earlier this month, Koehler appeared to suggest in a radio interview that the German military was stationed in Afghanistan in part to defend economic interests. The remarks exposed the president to fierce criticism and rekindled a debate in Germany, where the majority opposes the military mission to Afghanistan. Koehler sought to back-pedal last week, and a spokesman said his comments had not been about Afghanistan in particular. Crucially, however, German Chancellor Angela Merkel did not publicly come out to voice her support for the president as he came under fire. The president only informed Merkel and her junior coalition partner Guido Westerwelle by telephone earlier in the day of his decision to resign, seen by many as an exaggerated response to his critics. Both leaders said they had tried unsuccessfully to change his mind. "I regret this resignation to the utmost," Merkel said. "I think the people in Germany will be very upset at the resignation, as Horst Koehler was a president of the people, of the citizens of Germany." Koehler's resignation increases the problems facing Merkel's fractious and unpopular centre-right coalition government, wrangling with unprecedented national debt and testing times for Europe's common euro currency, as well as international criticism for not priming the economic pump. Merkel went on to praise the former head of the International Monetary Fund for his international experience and advice, especially during the financial and economic crisis. The chancellor also defended her decision not to speak out in support of Koehler during the previous week. "I spoke to the president frequently about the fact that respect for our constitutional institutions means we do not comment upon one another," Merkel said. This is the first time in German postwar history that a president has resigned. The speaker of Germany's upper house of parliament, Jens Boehrnsen, is to fill the post until a successor is chosen. --SPA 22:39 LOCAL TIME 19:39 GMT www.spa.gov.sa/787382