An activist who removed a mural painted by the reclusive British street artist Banksy from a war-ravaged building in a Kyiv suburb could face up to a dozen years in prison for theft, the Ukrainian authorities said in a statement released on Facebook.

The mural, showing a woman in a bathrobe wearing a gas mask and holding a fire extinguisher, garnered widespread attention when it appeared in the Kyiv suburb of Hostomel in November. It was one of seven artworks painted by Banksy on war-ravaged buildings in and around Kyiv.

On Dec. 2, a group of activists removed the mural, the police said in a statement. The authorities arrested several people in connection with the removal.

The statement, put out by the Ministry of Internal Affairs on Monday, said that the mural was valued at more than 9 million Ukrainian hryvnia, the national currency, or about $245,000. It said one activist, described as the organizer, could face up to 12 years in prison for removing the mural.

While the police did not identify the individual who could face jail time, one of the activists, Serhiy Dovhyi, had previously said that he was facing a criminal investigation for removing the work. Mr. Dovhyi said in an interview with The New York Times last month that he intended to auction it and donate the proceeds to the Ukrainian Army.

In the interview, he defended his actions, saying the artwork had to be saved because the wall on which it was painted was scheduled to be demolished. He described the act of removing the graffiti, which he documented in videos, as an additional act of performance art that might add to its value.

“Street art, in contrast to a piece of art in the Louvre, doesn’t belong to anyone,” Mr. Dovhyi told The Times.

The authorities, however, maintained that the mural should have remained on the wall, to be part of a future memorial or building.

It isn’t the first time ownership of one of Banksy’s works has been in dispute. In 2014, a Banksy painting appeared on a piece of plywood secured to the Broad Plain Boys Club in Bristol, England. The club’s owner, Dennis Stinchcombe, planned to auction the painting to raise money for the club, but the city stepped in and claimed it owned the depiction of a couple embracing and staring at their cellphones. In a rare public move, Banksy wrote a letter saying the art should be used to help the club.