A Belarusian military adviser is reported to have been shot dead in Yemen's capital, Sanaa.
The man, who local officials said was working with the Yemeni army, had just left a hotel in the south of the city with a colleague when two unknown gunmen on a motorbike opened fire.
His colleague was badly wounded.
Initial reports said they were Russian, but Russia's embassy said the victims were in fact Belarusians who had been working in Yemen on private contracts.
The Belarusian foreign ministry said it was checking the reports, but could not confirm the victims were from Belarus.
Earlier, a Russian embassy official noted that military co-operation with Yemen had been "suspended for the time being", and that there were no instructors in the country.
The Yemeni army has frequently in the past employed foreign advisers, including Russians.
'Presidential security force'
The manager of the Amsterdam Hotel, Mohammed al-Shami, said the two victims and two other men he said were Russian had been staying there for about four months. On Tuesday, he added, they had been dressed in civilian clothes and waiting for a taxi when the shooting took place.
"We heard the shooting. When we rushed out, we found the two in a pool of blood," he told the AFP news agency.
Two vehicles from the nearby presidential palace arrived about 10 minutes after the attack and took away the victims and their two colleagues, Mr Shami said.
Yemeni security sources told the Reuters news agency that the Belarusians were attached to a presidential security force and had been in Sanaa for nearly a year.
Last week, a Yemeni MP representing Zaidi Shia rebels in the country's north died in a similar attack. Gunmen riding a motorbike shot Abdul Karim Jadban outside a mosque in Sanaa.
Such killings are mostly blamed on militants linked to al-Qaeda.