The move is expected to harm his opposition challengers, including firebrand Alexey Navalny.
Other host countries have overwhelmingly used public funds to pay for construction of needed venues.
Nation's only independent polling agency said it may have to close; critics see larger crackdown.
The Russian government has gotten business powerhouses to foot more than half of the $51B bill.
Most of the projects the tycoons are involved in are not profitable — and many businessmen are making no secret of the losses they are incurring.
Talks come amid concerns that Moscow could soon provide Damascus with advanced missiles.
Russia will be a guarantor of world security, he said at the annual military parade on Red Square.
Putin made his short speech at the culmination of Victory Day, marking the defeat of Nazi Germany 68 years ago.
Vladislav Surkov's ouster followed feud with investigators of innovation project.
About 20,000 protesters thronged Bolotnaya Square, a year after a protest at the same spot turned violent.
