Moscow spent more than 53 billion rubles ($1.04 billion) supplying a separatist rebellion in east Ukraine and at least 220 Russian soldiers have been killed there, a report by Russian opposition activists said Tuesday.

The report was the last project of murdered Kremlin critic Boris Nemtsov, who used open source information and interviews with families to paint a picture contradicting Moscow's argument that no serving Russian troops are fighting in Ukraine.

Nemtsov was shot dead in central Moscow in February and members of his party, the liberal RPR-Parnas, and several opposition journalists helped finish the 65-page report.