A group of Qatari state-linked investors and three Japanese power firms have signed an agreement to study the possibility of developing projects in Turkey's Afsin Elbistan region, one of the Qatari firms said in a statement on Sunday. The Afsin-Elbistan region holds up to 45 percent of Turkey's reserves of lignite, or brown coal, and Turkish authorities have been keen to attract investment into the region to help meet growing electricity demand.