The Azeri courts issued a pardon for Azeri military officer Ramil Safarov after he was extradited from Hungary. He was sentenced to life in prison by a Hungarian court for killing Armenian officer Gurgen Markaryan in 2004.
Rupert Colville, a spokesman for the U.N. High Commissioner for Human Rights, said Safarov's attack on Markaryan was clearly ethnically motivated.
"International standards regarding accountability for serious crimes should be upheld," he said in a statement Friday. "Ethnically motivated hate crimes of this gravity should be deplored and properly punished, not publicly glorified by leaders and politicians."
NATO Secretary-General Anders Fogh Rasmussen met Friday with Azerbaijan's President Ilham Aliyev as part of his tour of the Caucasus.
Armenia and Azerbaijan have gone to war over the disputed territory of Nagorno-Karabakh. Both sides exchanged fire over the territory earlier this year.
Rasmussen said peaceful reconciliation was the only to resolve ongoing issues.
"The only way forward is through dialogue, compromise, and cooperation," he said in a statement from Baku.