Azerbaijan's Defense Ministry said that an Armenian sniper shot dead an Azerbaijani army officer on the border between the two countries, which have been locked in a three-decades long dispute over Azerbaijan's breakaway region of Nagorno-Karabakh.
There are frequent clashes along the separatist ethnic-Armenian controlled Nagorno-Karabakh front line and along the border between Armenia and Azerbaijan.
A shaky 1994 cease-fire ended a conflict between the two countries over the region, which left some 30,000 dead.
The July 20 incident came as Nagorno-Karabakh reelected on July 19 its separatist leader Bako Sahakian for a second presidential term in elections Baku quickly denounced as "illegal."
At least 11 soldiers from both sides have been reported killed in a series of incidents along the border since early June.
Based on reporting by AFP and Interfax