BERLIN - Former German President Horst Koehler passed away at the age of 81 in the early hours of Saturday after an illness, according to the Office of the Federal President of Germany.

Koehler, being German president from July 2004 to May 2010, unexpectedly resigned from the post following criticism of his comments concerning the overseas operations of Germany's armed forces.

German President Frank-Walter Steinmeier expressed his condolences to Eva Luise Koehler on Saturday regarding her husband's death and appreciated Koehler's service and contributions to the country.