Rescuers digging on Monday through the rubble after Morocco's deadly earthquake warned that the traditional mud brick, stone and rough wood housing omnipresent in the High Atlas mountains reduced the chances of finding survivors. "It's difficult to pull people out alive because most of the walls and ceilings turned to earthen rubble when they fell, burying whoever was inside without leaving air spaces," a military rescue worker, asking not to be named because of army rules against speaking to media, said at an army centre south of the historic city of Marrakech not far from the quake epicentre. Morocco's most powerful earthquake since at least 1900 has killed at least 2,497 people, the state news agency said in its latest update of the human toll on Monday, with thousands more injured and many still missing.