On Saturday morning, early entry into Belarus was observed by Wagner fighters, according to a monitoring group.
The mercenaries and Minsk’s own armed forces would engage in combined military training exercises, according to the Belarusian Defence Ministry.
At least 60 trucks, buses, and other huge vehicles entered the country in eastern Europe with police present, according to the independent monitoring organisation Belaruski Hajun, which keeps tabs on military operations.
The group did not immediately provide photos or videos of the vehicles but said they had license plates from Russian-occupied areas of eastern Ukraine.
Wagner mercenaries fought alongside Russian troops in Ukraine until a short-lived mutiny by leader Yevgeny Prigozhin last month.
Prigozhin was forced into exile in Belarus, where president Aleksandr Lukashenko also offered to station some of the mercenary fighters.
The convoy headed toward a military base outside Osipovichi, a town 230 kilometers (142 miles) north of the Ukrainian border.
Satellite images analyzed this month showed rows of tent-like structures that appeared to have been built at the base between June 15 and June 30.
The president of Belarus, Alexander Lukashenko, said at the time that Minsk could use Wagner’s experience and expertise, and that he had offered the fighters an ‘abandoned military unit’ to set up camp.
That same week, a leader of an anti-Lukashenko guerrilla group said construction of a site for the mercenaries was underway near Osipovichi.
A spokesperson for Ukraine’s State Border Guard Service the force also had observed ‘some groups’ of Wagner fighters crossing from Russia into Belarus.
The Belarusian Defense Ministry said in an online statement late Friday that it had developed a ‘road map’ with Wagner’s management for joint training exercises drills by the nation’s military personnel and the private mercenaries.
Earlier Friday, the Defense Ministry said Wagner fighters had begun training Belarusian soldiers.
A TV channel affiliated with the ministry showed footage of fighters in black masks instructing soldiers on how to shoot and provide first aid.