MOSCOW — The general director of the Mystetskyi Arsenal in Kiev, the largest art institution in Ukraine, has been accused of censorship and catering to church and state after she painted over in black a mural she had commissioned from the contemporary artist Volodymyr Kuznetsov.

In an appeal posted on Thursday a Kiev-based group called the Art Workers’ Self-Defense Initiative called for a boycott of Mystetskyi Arsenal and said that the general director, Natalia Zabolotna, had used “Great and Grand,” the exhibition from which she banned Mr. Kuznetsov, as a vehicle for “presenting culture as an attractive object working for the fusion of state and church, which in this instance is encroaching even on artistic space.”

The exhibition, which presents 1,000 pieces, including icons, opened on July 26 as part of celebrations marking the 1,025th anniversary of events that brought Christianity to Ukraine and Russia. Politicians and clergymen attended the opening. President Vladimir V. Putin of Russia and the Russian Orthodox Patriarch, Kirill I, were in Kiev together on Saturday to mark the anniversary with the Ukrainian president, Viktor Yanukovych. Mystetskyi Arsenal, or Art Arsenal, is housed in a former tsarist-era weapons arsenal just opposite the Kiev Monastery of the Caves, one of the centers of Orthodoxy.

Mr. Kuznetsov wrote on his Facebook page on July 25 that he had arrived at the arsenal to find that he was was not being allowed to complete the mural, “Koliivschina: Judgment Day.” Then he learned that it had been painted over. In the work he depicts corrupt clergymen and bureaucrats burning in hell.

Ms. Zabolotna told Levy Bereg, or Left Bank, a popular Ukrainian news Web site, that Mr. Kuznetsov had violated the terms of his commission which, she said, was supposed to be devoted to events in the town of Vradievka, where policemen were accused of raping and brutally beating a young woman. She described his mural as “a slap personally in my face” and “a provocation against visitors to the exhibition” and said that Mr. Kuznetsov had apparently been influenced by plans to hold a protest near the arsenal. About 10 protesters were arrested in front of the art space when they demonstrated on July 26 against the “clericalization of Ukraine.”

“You can call this my own performance,” she said of painting over the work. “I don’t regret what I did.” She added that she was “speaking out against the impudence of certain artists.”

Oleksandr Soloviev, a respected Ukrainian curator and deputy director of Mystetskyi Arsenal, quit after the incident. Ms. Zabolotna did say that Mr. Kuznetsov would still be paid for his work. In a blog post on the Left Bank site the artist described her actions as “an act of vandalism and bureaucratic grovelling.”

In 2012, Ms. Zabolotna organized Kiev’s first international contemporary art biennale at the arsenal, and she plans to open a museum of Ukrainian art in 2014.