The armed forces of Russia and Serbia will hold a joint military training in Belarus from September 10 to 15, according to the Moscow RIA news agency.
Serbia's Defence Ministry failed to confirm the information to the Voice of America (VOA).
Radio Free Europe (RFE) quoted Belarus Defence Minister's post on social Telegram network saying the military exercise 'Slavic Brotherhood 2020' would take place in the country and that the Russian and Serbia's armies would take part.
The news comes amid some confusing messages from Belgarde and Moscow following the White House meetingparticipated by Serbia's President Aleksandar Vucic and Kosovo's Prime Minister Avdulah Hoti who signed some documents witnessed by the US President Donald Trump.
Some parts of the agreement are said to have imperilled Belgarde relations with both Moscow and Beijing.
Russian media quoted high-ranked Moscow sources as being unhappy with the deal, while Beijing has so far been silent.
Also, the exercise is scheduled amid huge protests in Minsk after what the opposition there said were rigged presidential election won by President Alexander Lukashenko, who has ruled the country for almost three decades.