UNITED NATIONS - The United Nations is "extremely concerned" by reports that medical facilities and vehicles were being used to carry out violence in Syria's 18-month conflict, a spokesman for UN Secretary-General Ban Ki-moon said on Tuesday.

"Medical facilities, equipment and personnel must not be targeted or used for military purposes," Ban spokesman Martin Nesirky said in a statement. "All parties involved in the conflict must respect international humanitarian law and ensure that civilians are not targeted."

Nesirky did not say whether it was forces supporting Syrian President Bashar Assad, rebels or both who were reportedly using or targeting medical facilities or vehicles, which could constitute a serious war crime.

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