MOSCOW — One of Russia’s most famous paintings, which depicts the czar Ivan the Terrible cradling his dying son, has been badly damaged in a Moscow gallery after a man drank vodka and attacked it with a metal pole, the police said.

The 1885 canvas, “Ivan the Terrible and His Son Ivan on November 16, 1581,” by the Russian realist Ilya Repin, portrays a grief-stricken Ivan holding his son after dealing him a mortal blow, an event whose veracity some Russian nationalists dispute.

The Tretyakov Gallery in central Moscow said a man had attacked the canvas just before closing time on Friday. He managed to get past a group of gallery employees, the gallery said, picked up one of the metal security poles used to keep the public back from the painting, and struck its protective glass covering several times.

The thick glass “was smashed,” the gallery said in a statement. “Serious damage was done to the painting. The canvas was pierced in three places.”