Climate-change protesters say they have been warned off the Mystery Creek Fielday site in Waikato for distributing woodchips to highlight Fonterra's use of coal-fired energy.
Auckland Coal Action said apart from the Glenbrook steel mill and the Huntly power station, Fonterra is the biggest user of coal in New Zealand.
Spokesperson for the protesters and former Green Party co-leader Jeanette Fitzsimons said security staff took photographs of them and ordered them off the site.
She said the police on-site had also told them they were not allowed on the public roads surrounding Mystery Creek.
Ms Fitzsimons said she didn't know if Fonterra had asked for the protesters to be removed but staff were upset by their presence, both this year and last year.
The group said it had been trying to talk to Fonterra for nearly two years about its huge use of coal, but two meetings have achieved nothing.
Organisers of the event said the climate-change protesters were asked to leave the event today because they were engaging in 'bandit marketing'.
Fieldays' general manager, Nick Dromgool, said people were distributing fliers in the carpark, which was not allowed.
He said Fonterra was not involved in asking the protesters to leave, and Fonterra had confirmed that.