The Toronto Symphony Orchestra cancelled two performances by Ukrainian-born pianist Valentina Lisitsa, citing concerns over her "deeply offensive" and "provocative" online remarks about the conflict in Ukraine.

Lisitsa, a Ukrainian-American who was scheduled to perform Rachmaninoff's Piano Concerto No. 2 with the TSO on Wednesday and Thursday, took to Facebook on Monday to accuse the Toronto Symphony (TSO) of censorship.

“Someone in the orchestra’s top management,” she wrote in a 1,000-word post, “likely after the pressure from a small but aggressive lobby claiming to represent the Ukrainian community, has made a decision that I should not be allowed to play.”

She also said she was accused of “inciting hatred on Twitter.”

Following the announcement, Twitter quickly responded with a barrage of tweets in her support, many of them with the hashtag #LetValentinaPlay. Bravo Niagara Festival of the Arts, which presented Lisitsa in concert in St. Catharines, Ontario, on Sunday night, tweeted: “In defence of #FreedomofSpeech #LetValentinaPlay … Music can’t be silenced!"

Lisitsa said the TSO will still pay her for the cancelled performances.

The TSO issued a statement Monday defending its decision to pull her from the lineup.

"Due to ongoing accusations of deeply offensive language by Ukrainian media outlets, we have decided to replace Valentina Lisitsa," said the orchestra's president and CEO Jeff Melanson.

"Valentina Lisitsa’s provocative comments have overshadowed past performances. As one of Canada’s most important cultural institutions, our priority must remain on being a stage for the world’s great works of music, and not for opinions that some believe to be deeply offensive."

The orchestra announced Monday that it had replaced Lisitsa with another pianist.

Lisitsa uses her Twitter account to frequently express her strong support of those fighting against Kiev forces in Ukraine. In more than 13,000 tweets aimed at more than 9,000 followers, she has posted sharp denunciations of the Western media and Ukrainian "neo-Nazis" mixed with graphic battlefront videos and images.

Until now, her political commentary has prompted little response by North American concert presenters or audiences. In October, a small group of protesters picketed in front of her recital at Heinz Hall in Pittsburgh.

Lisitsa, 41, was born in Kiev but moved to the United States after the breakup of the Soviet Union in 1991.

Often called “the web’s favorite pianist,” she launched her career through a YouTube channel, which now has received some 43 million visitors.