The 64-page dossier was published on the Open Russia website on May 12 and draws on research conducted by Nemtsov before he was shot to death in February this year.
The document catalogues at least 150 Russian soldiers whom it says were killed fighting in Ilovaisk, a small town in the Donetsk region of east Ukraine, in August 2014.
It also claims that 70 more Russian military personnel perished while fighting in Debaltseve this January and February.
According to Radio Free Europe/Radio Liberty (RFE/RL), the report alleges that families of those killed in action were paid 2 million rubles (US$ 39,000) by the Russian government for their silence.
It also claims that many of the soldiers were asked to resign from the Russian army before leaving to fight in Ukraine in order to conceal their involvement.
Ilya Yashin, who finalized the report, said at a press conference in Moscow that it was important to speak out against the “isolationist policies of [Russian President] Vladimir Putin”.
Putin and the Russian government have denied the involvement of official Russian forces in east Ukraine, saying that Russian nationals fighting in the region are acting independently.
In the aftermath of the report’s publication earlier this week, Russian opposition activists who helped prepare it claimed that their Paypal account, used for accepting donations, had been blocked. Paypal, a US-based service, told RFE/RL that they did not operate accounts set up to collect contributions to campaigns of a political nature.
Boris Nemtsov, an outspoken critic of the Kremlin, was shot four times in the back as he walked near the Kremlin in Moscow in February. Allies speculated that he had been killed for holding sensitive information about Russia’s involvement in Ukraine.
Meanwhile, President Putin has publicly called the murder a “disgrace”.
