The Foreign Ministry on Monday expressed concerns over Azerbaijan's decision to pardon a convicted killer Hungary sent back to Azerbaijan to serve his prison sentence.
Lieutenant Ramil Safarov was given a life sentence in 2006 by a Hungarian court after he confessed to killing Lieutenant Gurgen Markarian, an Armenian, while both were in Hungary for a 2004 NATO language course.
Azerbaijan and Armenia have been locked in a long-standing feud over the mountainous territory of Nagorno-Karabakh.
Azerbaijan's president pardoned and freed Safarov after he was returned home on Friday, prompting Armenia to break off diplomatic ties with Hungary.
Hungarian authorities insisted that they returned Safarov, 35, to Azerbaijan only after receiving assurances from the Azeri Justice Ministry that Safarov's sentence, which included the possibility of parole after 25 years, would be enforced.
Russia's Foreign Ministry, an important broker in the Armenia-Azerbaijan feud, condemned Safarov's release in a statement Monday, saying that it hampers peace-keeping efforts by Russia and other international mediators.
"We believe that these actions of Azeri as well as Hungarian authorities contradict internationally brokered efforts, of the OSCE's Minsk group in particular, to ease tensions in the region," the ministry said.
The White House also has criticized the decision to free Safarov.
About 150 demonstrators gathered in Armenia's capital, Yerevan, over the weekend to set the Hungarian flag ablaze and demand an end to talks on resolving the Nagorno-Karabakh issue.
During his trial in Budapest, Safarov said the conflict was at the root of his actions.
He used an ax to kill Markarian while the victim was sleeping in a dormitory room. Safarov said Markarian had repeatedly provoked and ridiculed him.