Madrid's major opera house Teatro Real, or simply El Real, called off some performances by the prestigious Bolshoi Ballet scheduled in May on Friday due to the Russian invasion of Ukraine and humanitarian crises it caused.

Thousands of people are believed to have been killed or wounded and more than 1 million refugees have fled Ukraine since Feb. 24 when Russian President Vladimir Putin ordered the biggest attack on a European state since World War II.

"The Teatro Real regrets not being able to count on this prestigious company, whose director, Vladimir Urin, has spoken out publicly in favor of Ukraine and against the war," it said.

The opera house already showed its support to Ukraine on Feb. 27, when in a performance of "Twilight of the Gods," the corpse of Siegfried was wrapped in the Ukrainian flag.

The invasion has led dozens of private companies, as well as a wide array of institutions, to either stop operating in Russia or cut ties with Russian counterparts.

The Madrid theater said it will reimburse the tickets it had already sold.