The Dairy Worker's Union is urging Fonterra to allow unions to have access to its sites in Malaysia and Sri Lanka, after the matter was discussed at an international conference of dairy sector unions.
Dairy Workers Union national secretary James Ritchie represented New Zealand at the Global Conference of Dairy Unions in Argentina.
He says since the last conference, which was held in Auckland in 2001, Fonterra has grown to be one of the world's biggest trans-national dairy operations and one of the biggest employers.
Mr Ritchie says this means unions internationally are noting how the company treats its staff and its attitude to employees' rights.
He says they noted with a great deal of concern the fact that Fonterra will not allow access to unions in Malaysia or Sri Lanka.
Mr Ritchie says Fonterra is not obligated to do that but it has an agreement with the International Union of Food Workers and the New Zealand Dairy Workers Union to observe international labour organisation standards where ever they operate around the world.
He says unions believe this implies the right for workers to have an opportunity to join unions and bargain collectively.
But Mr Ritchie says Fonterra says workers have that right if they want to go out and seek it, but the company will not facilitate access.
He says access of unions to offer union membership in such countries is very important otherwise workers are too afraid to go out and approach a union.
Fonterra's human resources head Jennifer Kerr says the company complies with International Labour Organisation conventions and local employment relations law in all the countries in which it operates.
But she says its agreement with the International Union of Food Workers does not cover access by union officials to Fonterra workplaces.
Ms Kerr says the company has been operating in Malaysia and Sri Lanka for many years and is a preferred employer there.
She says Fonterra has cordial relations with its staff in both countries and it believes they are happy to deal with it directly.
And Ms Kerr says it supports the right of its employees in all countries to join a trade union if they wish.