The agency said it received a complaint that the Nova Scotia Teachers Union posted election advertising in the Chronicle Herald without registering as a third party, identifying itself or stating that the ad was authorized by the union.
Elections Nova Scotia said an investigation has determined the material is election advertising and told the union it must register as a third party and comply with the requirements of the legislation.
It said the union has refused to register, but has agreed to stop all advertising and take down a website mentioned in the ads until Wednesday, the day after the vote.
Elections Nova Scotia says the investigation is ongoing.
President Shelley Morse said the union is co-operating with the investigation, but adds it believes it did not violate the Elections Act.
Morse said the ad showed a teacher in a classroom and described how she spent $600 of her own money on supplies for 28 students.
"We were talking about what is happening in our classrooms, and we didn't believe that had anything to do with any of the candidates," said Morse. "I think it will be determined that the ads that we were running were not election advertising.
"We expect to be vindicated at the end of the process."
Morse said the Teaching Profession Act gives the union the authority to advance and promote public education in the province. She said the website contained five questions related to the education system that it was encouraging the public to ask their candidates.
"The questions were broad questions about education, just to have those candidates thinking about education and what's best for the students in Nova Scotia," she said. "We didn't see that publicizing those question would amount to election advertising."
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