Western leaders have widely blamed Putin for the sudden death of his most prominent critic.
The crowd lining the streets in Moscow chanted "no to the war" in defiance of the Russian president.
The Russian president there would be "tragic" consequences for the West in major speech on the Ukraine war.
"Putin is the leader of an organised criminal gang," Yulia Navalnaya said.
Trouble stirs in Europe after French president Emmanuel Macron claimed the West would not rule out sending soldiers.
But the separatists stopped short of requesting to officially join Russia.
The late Kremlin critic also made a sad prediction for 10 years' time.
It's not just about what is happening on the frontline.
A very bizarre war of words unfolding here.
The UK's foreign secretary was not the only one to go in for a face-to-face confrontation with Sergei Lavrov at a G20 meeting on Wednesday.