The U.N.'s secretary-general has made a strong appeal to halt the flow of arms into Syria and warned that the crisis threatens stability in the entire region.

Ban Ki-moon says he is "deeply concerned" about the continued flow of arms to both the Syrian government and opposition forces, and said a "political solution" is "the only way out of the crisis."

Speaking at an international conference on democracy in Strasbourg, the UN chief described as "extremely dangerous" escalating conflict along the Syrian-Turkish border and the crisis' impact on Lebanon.

In his speech Monday to the World Forum for Democracy Ban also said the U.N.-Arab League envoy to Syria Lakhdar Brahimi would return to the region this week to continue international efforts seeking political transition in Syria.