The men are officially accused of plotting a terrorist attack, and authorities have said they belong to the Wagner Group, a private Kremlin-linked security and paramilitary organization.
Denis Korotkov, an investigative journalist for the Russian newspaper Novaya Gazeta, told DW that at least half of the detained men can be linked to the Wagner Group.
Watch video 01:32 Tens of thousands rally for opposition
Belarusian political scientist Valery Karbalevich said authorities fear mass demonstrations in support of Tikhanovskaya, with thousands rallying in Minsk and other cities, and have aimed to put a stop to them.
Piotr Petrovsky, an expert at the Belaya Rus think tank which is closely affiliated with the Lukashenko regime, wrote on Facebook that the arrest of the Russian men had clearly shown that many opposition candidates were simply puppets of the Kremlin.