UN heritage agency UNESCO on Thursday urged forces fighting in Syria to avoid damage to historically important cultural sites, in particular in the country\'s second-largest city Aleppo. \"In light of escalated violence in the vicinity of several historic urban areas in Syria, the director-general of UNESCO Irina Bokova reiterates her appeal... to all parties involved in the conflict to protect all Syrian cultural heritage,\" the agency said in a statement. It said UNESCO was \"particularly alarmed over reports of heavy fighting in Aleppo\", which is a world heritage site, and was concerned over other heritage sites including the Crac des Chevaliers crusader castle and the ruins of Palmyra. The statement said UNESCO had also alerted international customs and police bodies to be on the lookout for stolen artifacts from the country. \"In the current context of civil strife, UNESCO is also particularly concerned about the risks of looting and pillaging of cultural property,\" it said.