Gunmen in the Yemeni capital of Sanaa on Tuesday rode by a hotel on a motorcycle and shot two Belarussian military advisers.
The attack killed one man and wounded another as the pair walked out of their hotel, the Dubai-based al-Arabiya television station reported.
The spokesman from the Russian Embassy to Yemen told Interfax that the two men were Belarussians, and said that one of them was killed and the other seriously injured.
Earlier media reports had said that the two men were Russian and that were both killed.
The Belarussian Foreign Ministry confirmed Tuesday afternoon that the advisers were Belarussian citizens working on "an official contract."
A representative from the Belarussian Defense Ministry said that he had no information about Belarus sending advisers to the Arab country.
The Russian Embassy said that the men were working as private military contractors and a Yemeni police spokesman confirmed that the pair were working for the country's Defense Ministry.
Much of the equipment used by Yemen's Armed Forces is Soviet or Russian-made and many Russian specialists are thought to be employed as advisers.
Yemen viewed by many as a training ground for radical Islamic extremists, particularly the international terrorist organization al-Qaida. It has been plagued by a power vacuum since long-time leader President Ali Abdullah Saleh stepped down in 2012 after an uprising.
A Yemeni Air Force strike in the country's south killed 12 suspected members of al-Qaida on Tuesday, Yemeni law enforcement agencies said.