He is the first casualty among Russian peacekeepers who were dispatched to the region last month after a ceasefire agreement signed on Nov. 10 ended three months of heavy fighting between Azerbaijan and ethnic Armenian forces.
Interfax news agency said the officer had died on his way to hospital from heavy wounds after a mine exploded near Nagorno-Karabakh's second city Shushi, which Azeris call Shusha.
The enclave of Nagorno-Karabakh is internationally recognized as part of Azerbaijan but is populated by ethnic Armenians. Some 2,000 Russian peacekeeping troops are now being deployed to the region.