Nationalists have vandalized a makeshift memorial to Russian opposition leader Boris Nemtsov on the site of his killing, but it has been quickly restored.

Nemtsov, a former deputy prime minister and a top critic of President Vladimir Putin, was shot and killed on Feb. 27 on a bridge near the Kremlin.

Mourners set up a memorial at the site of his slaying with Nemtsov's picture and a plaque reading "Nemtsov Bridge." Earlier this week, a group describing themselves as patriots supportive of the Russia-backed rebels in Ukraine vandalized it, placing stickers denouncing Nemtsov as a "traitor of Russian interests" and spraying the plaque with paint.

Nemtsov's supporters have restored the memorial.

Russian police have arrested five Chechens accused of involvement in the killing, but haven't named a mastermind yet.