Valentina Lisitsa, who has a huge online following, has criticised western journalists for supposed bias in covering events in Ukraine

A pianist has been struck off the concert programme with a Canadian orchestra for expressing her support for pro-Russia separatists in eastern Ukraine.

Valentina Lisitsa, a Ukraine-born pianist, was scheduled to play Rachmaninov’s Piano Concerto No 2 with the Toronto Symphony Orchestra on Friday night, but her performance was scrapped amid “ongoing accusations of deeply offensive language” on Twitter, said the orchestra’s president, Jeff Melanson.

Lisitsa had posted graphic images and angry rhetoric about the conflict in east Ukraine and criticised western journalists for supposed bias in covering the events. Canada has a large Ukrainian diaspora.

“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,” Melanson said.

Lisitsa said she never posted any threats or anything else illegal and she had not been planning to make any political statement during the concert. She said her Twitter activity was borne of a feeling that the coverage of events in Ukraine had been skewed in favour of the new government in Kiev.

In Toronto, there was mixed reaction to the move. One columnist in the Toronto Star said the ban created a “dangerous precedent” and “has made a mockery of the arts in this city”.

The orchestra initially said it would replace Lisitsa with another pianist, then removed the Rachmaninov concerto from the concert programme altogether.

Lisitsa has a huge online following, and her YouTube videos have viewing figures in the millions. In January she played a Prokofiev piano concerto with the London Symphony Orchestra at the Barbican Centre.

Lisitsa said she planned to give a free concert at a church in Toronto on Friday instead of the official performance. Later, however, she said the performance had been cancelled. She wrote on Twitter: “I feel like I am taking part in some Orwell reenactment. Just wow. Surreal.”

It is the latest instance of the conflict in Ukraine causing artistic upheaval. The Russian rock musician Andrey Makarevich was subjected to a smear campaign in Russian media after playing a concert in territory held by the Ukrainian government in east Ukraine. The popular Ukrainian band Okean Elzy have stopped playing concerts in Russia since the Maidan revolution in Kiev, and the Ukrainian government has banned films that are perceived to glorify Russia’s military.

In the highest-profile classical music case, the Russian opera star Anna Netrebko caused controversy when she donated 1m roubles (£13,400) to the Donetsk opera house, handing the money over to a separatist leader and being photographed holding the flag of the Russian-backed separatist territory Novorossia.

During a run of performances at the Metropolitan Opera in New York, she was subject to a protest at the curtain call by an angry Ukrainian. However, she has not had any performances cancelled.

Netrebko said she wanted to help the singers and had not realised the flag she was given was a separatist flag. The Donetsk theatre confirmed to the Guardian that it had received the money and said it was much needed.