The United Nations on Wednesday appealed to warring factions in Syria's bloody civil war to protect the country's cultural heritage, warning of widespread looting and damage at historical sites caught up in the conflict. A joint statement from UN Secretary General Ban Ki-moon, UNESCO director Irina Bokova and international mediator on Syria Lakhdar Brahimi called on all sides to "halt immediately all destruction of Syrian heritage, and to save Syria's rich social mosaic and cultural heritage." The officials condemned the use of historical sites for military uses, including four World Heritage Sites -- Palmyra, Crac des Chevaliers, the Saint Simeon Church in the ancient villages of Northern Syria and Aleppo, including the Aleppo Citadel. "As the people of Syria continue to endure incalculable human suffering and loss, their country's rich tapestry of cultural heritage is being ripped to shreds," the statement said. "Archaeological sites are being systematically looted and the illicit trafficking of cultural objects has reached unprecedented levels," it added. The UN urged any art dealers or tourists who come across Syrian artifacts to be cautious. "We appeal to all countries and professional bodies involved in customs, trade and the art market, as well as individuals and tourists, to be on alert for stolen Syrian artifacts, to verify the origin of cultural property that might be illegally imported, exported and/or offered for sale," the statement said. Syria's World Heritage sites had "suffered considerable and sometimes irreversible damage" the statement warned. "All layers of Syrian culture are now under attack -- including pre-Christian, Christian and Muslim." The UN said it had also received reports that precious historical sites were being targeted for "ideological reasons." "Human representations in art are being destroyed by extremist groups intent on eradicating unique testimonies of Syria's rich cultural diversity," it warned. "The destruction of such precious heritage gravely affects the identity and history of the Syrian people and all humanity, damaging the foundations of society for many years to come," the statement added.