YEREVAN/BAKU (Reuters) - Armenian Defence Ministry said on Sunday it was checking reports about combatants from Syria who are allegedly fighting for the Azerbaijan’s side in clashes over the breakaway Nagorno-Karabakh province. Hikmet Hajiyev, the foreign policy aide to the Azeri president, dismissed the report carried by the Britain-based Syrian Observatory for Human Rights as “nonsense”. At least 16 military and several civilians were killed on Sunday in the heaviest clashes between Armenia and Azerbaijan since 2016, reigniting concern about stability in the South Caucasus, a corridor for pipelines carrying oil and gas to world markets.