Plovdiv, one of the 2019 European capitals of culture, has become embroiled in a homophobia scandal as local officials attempt to remove the head of the organising committee over a photographic exhibition featuring LGBT themes.

Officials in the Bulgarian city, which is co-hosting the 2019 edition of the European capital of culture with Matera in Italy, said a “Balkan Pride” photo exhibition due to open in July should be stopped.

“We don’t want them to do it. And we will stop them, using all legal and, if required, illegal means,” said Alexander Sidi, an MP from the nationalist VMRO party.

On Monday, the city council will vote on whether to recommend the removal of the municipal cultural foundation head, Svetlana Kuyumdzhieva. It hopes to force the city’s mayor into action.

The exhibition will feature photographs from past gay pride events that took part across the Balkan region, plus a concert and a discussion forum. It is organised by the Glas foundation, an LGBT rights group.

“This is the same as carrying out a gay pride parade in Plovdiv,” Borislav Inchev from VMRO-Plovdiv, said last week. “I am very curious what would happen if a teacher made a mistake and sent her schoolchildren to see the exhibition. What would they see? How would she explain it?”

Kuyumdzhieva said the intervention by local councillors was an “ugly provocation”, noting that the European capital of culture project required a guarantee of political non-interference. “This could seriously damage the reputation and image that we’ve been building in the past five years. Such interference with the programme can only be treated as discrimination and censorship,” she told the Guardian.

VMRO, one of the three ultranationalist parties currently in government in Sofia, has gained the public support of 21 out of 50 members of the city council, including the nominally leftwing Bulgarian Socialist party and the local United for Plovdiv coalition.

“Plovdiv is more or less a conservative city. Other projects should have been a priority,” said Evelin Paraskov, of United for Plovdiv. He claimed that while he was backing the removal of Kuyumdzhieva, his main problem was the lack of transparency over the spending of public money by Plovdiv 2019, rather than the LGBT content.

There are concerns about rising homophobia in Bulgaria. A March survey ordered by Glas showed that only one in three Bulgarians would not mind if their neighbour was gay. In March a man broke into Rainbow Hub in Sofia, the first LGBT community centre in the country, and vandalised it. The centre had a window smashed in a separate attack on Friday.

Earlier this year there were two attacks on LGBT women in Sofia provoked by their appearance, according to a local NGO. Last month graffiti reading “No to gay propaganda in Plovdiv” and obscenities were sprayed on the walls of the Plovdiv 2019 headquarters.

Simeon Vassilev, of Glas, said his organisation would find a way to carry out the project. “Politicians seem to not understand the content of a cultural product, and they fail to realise that the European capital of culture should not be politicised and filled with intrigues,” he said. “The theme of Plovdiv 2019 is ‘together’. Where is the togetherness at the moment?”