German President Horst Koehler started on Tuesday his one-week official tour to Asia, Xinhua quoted the president's office as announcing. Koehler will visit Kazakhstan and hold talks with Kazakh President Nursultan Nazarbayev in the country's capital city of Astana. The president will also visit Mongolia and China. During his stay in China, Koehler will attend the opening ceremony of the Paralympics, the Olympic Games for athletes with disabilities.