"The union has shared information that we agreed would be confidential.
"While we continue to ensure that we respect the agreement we have with the union for consultation information to remain confidential, we're disappointed that the union has not respected this with the information it has shared [at the rally]," a Mondelez spokeswoman said.
When contacted, E tu industry strategy director Neville Donaldson denied breaching confidentiality.
The machinery comment was not part of the official consultation process, he said.
"It was just general discussion. But even if it was [part of consultation] it's not exactly what you'd call trade secrets.
"If that's all they've got to moan about they haven't got a hell of a lot," Donaldson said.
"We've got way more things to be concerned about, like their refusal to give us genuine information to be able to come up with alternative proposals.
"That plant, whether it be old or otherwise, is currently producing a lot of profit."
Mondelez did not specify which part of the leaflet breached confidentiality, but most of the leaflet concerns its international actions.
At Saturday's rally, Cull called out the multinational for refusing to engage with the city council over the closure proposal.
It cited the need to complete the formal consultation with workers first, Cull said.
In response, Mondelez's spokeswoman said the company was committed to working through the consultation period with staff and the union.
"In regards to working with the council, we will absolutely do so, once the outcome of consultation is known."
About 200 people attended the rally in the Octagon to urge a change of heart from the multinational.
Mondelez has proposed closing the Dunedin factory and laying off more than 360 workers.
Its final decision is expected later this month, but there is no firm date.
