BERLIN (AFP) - German President Christian Wulff vowed Sunday that Germany would continue to support Afghanistan after the troops have left, as he made a surprise trip to Kabul for talks with President Hamid Karzai. "I have come to Afghanistan to make clear: Germany will not leave Afghanistan in the lurch," Wulff stressed upon arriving for the first official visit of a German head of state to Kabul in 44 years. Meanwhiel, Afghanistan's intelligence agency said Sunday it had launched an investigation into allegations that its personnel had beaten an inmate nearly to death while interrogating him in the province of Khost. The probe ordered by the National Directorate of Security (NDS) follows media reports that said the beating of the inmate, a preacher, caused kidney failure and other internal injuries.