More than 50 Ukrainian writers and artists, a cross-party group of UK MPs, and a former New Zealand prime minister have urged the Royal Ballet and Opera to drop the Russian opera singer Anna Netrebko from its new London season.

Netrebko is due to perform in the RBO’s production of Tosca next month. In a letter to the Guardian, the signatories describe her as a “longtime symbol of cultural propaganda for a regime that is responsible for serious war crimes”.

They suggest the RBO has put itself on the wrong side of history by inviting Netrebko to perform in title roles at a time when Russia has escalated its attacks “on peaceful Ukrainian cities and civilians” and is trying systematically to erase Ukrainian culture.

“The Royal Opera now faces a defining choice: between status and responsibility, between profit and values, between silence and conscience. We urge you to remain, as you consistently have, on the ethical side of art – and of history,” the letter adds.

Signatories include the Ukrainian novelists Andriy Kurkov and Serhiy Zhadan, the Oscar-winning film-maker Mstyslav Chernov and the chef and author Olia Hercules. The former New Zealand prime minister Helen Clark has also backed the letter along with a group of MPs, and the French intellectual Bernard-Henri Lévy.

The Royal Opera House and Netrebko declined to comment. Earlier this month the RBO pulled its production of Tosca at the Israeli Opera in Tel Aviv after almost 200 Royal Opera and Ballet members signed an open letter criticising the organisation’s stance on Gaza.

The RBO’s chief executive, Alex Beard, explaining his decision, denied accusations of double standards, after the opera house confiscated a Palestinian flag in July from a performer. In 2022 it showed the Ukrainian flag as a symbol of solidarity after Moscow’s full-scale invasion.

Beard said last week: “Our support for Ukraine was aligned with the global consensus at the time. As the world’s geopolitics have become more complex, our stance has changed to ensure that our actions reflect our purpose and values.”

The Labour MP Alex Sobel, chair of the parliamentary all-party group on Ukraine, said he was “deeply troubled” by the RBO’s invitation to Netrebko and its apparent reduction in support for Kyiv.

“You can’t explain it as ‘complex geopolitics’. It’s not complex. It’s simple. Don’t invite Russian supporters of the regime to perform. Ukraine is fighting for all our freedoms. This is adding insult to injury,” Sobel said.

The Conservative MP John Whittingdale and the Labour MP Emily Thornberry have met Beard privately to discuss Netrebko’s participation in the 2025-26 season, and have also written to him about it.

“Anna Netrebko may be a fine soprano but she has previously shown support for Russian separatists in Ukraine and has said nothing to condemn Russian brutality since a single statement over three years ago,” Whittingdale said.

The MP added: “I am sorry that the Royal Opera House has reversed its position by inviting her to perform, and hope at the very least that she will make clear her condemnation of Putin and his regime before taking the stage in London.”

Ukraine’s first deputy foreign minister Sergiy Kyslytsya, who organised the letter, said the ROB should replace her with a singer “not associated with a criminal regime”.

Netrebko is one of the world’s best-known sopranos who draws full houses for her performances at leading opera houses globally. She made her name at the Mariinsky theatre in St Petersburg, whose director, Valery Gergiev, is an ardent supporter of Russia’s president, Vladimir Putin.

In 2014 Netrebko made a donation to Donetsk’s opera house after Russia seized the city as part of its covert armed takeover of parts of eastern Ukraine. She met a pro-Kremlin former Ukrainian politician and was photographed holding the separatist flag of “Novorossiya”, later saying she did not understand what the flag meant.

The Guardian letter asked: “Can the Opera credibly claim neutrality and integrity while offering its stage to someone who, in 2014, publicly waved the flag of ‘Novorossiya’, the Kremlin’s separatist project in Ukraine’s Donetsk region, parts of which remain under Russian military occupation?”

A longtime Austrian citizen and resident, Netrebko issued a statement in March 2022 condemning the war in Ukraine. “My thoughts are with the victims of this war and their families,” she posted on Facebook, saying she was not a member of a political party nor “allied with any leader of Russia”.

“I acknowledge and regret that past actions or statements of mine could have been misinterpreted,” she added, saying she had met Putin “only a handful of times” at awards ceremonies and the Olympics. “I love my homeland of Russia and only seek peace and unity through my art,” she wrote.

Her general manager, Miguel Esteban, said Netrebko had “never shown support for Russian separatists” and had condemned the war in three social media statements and two interviews. She had not returned to Russia since the full-scale invasion, he added.

Netrebko has carefully avoided directly criticising the Russian president, who in 2008 gave her the honorary title of “people’s artist”. In March 2022 the Metropolitan Opera in New York cited her failure to condemn Putin for its decision to drop her from a run of Turandot, with her role given to a Ukrainian artist. Other invitations dried up.

She has subsequently made a comeback, appearing at the Vienna State Opera and singing to a full house at La Scala in Milan. She is scheduled to perform for four nights at the Royal Opera House in Covent Garden from 11 September, with another appearance in December, starring in Turandot.

• This article was amended on 14 August 2025 to add a comment from Anna Netrebko’s manager, Miguel Esteban, that was received after publication.