Listen: Damien O'Connor on potential Westland Milk Products sale

Minister of Agriculture Damien O'Connor is not happy with the potential sale of Westland Milk Products, describing it as "a sad day" for the West Coast.

O'Connor told The Country's Jamie Mackay he hoped the farmer-owned co-operative remained New Zealand-owned, rather than going to Chinese dairy giant Yili.

"I don't like the idea of selling ... it's a proud company [and] the biggest company owned by West Coasters," said O'Connor.

"Most of the other companies on the coast have been owned by people from elsewhere and now the proposal to sell it - it's a sad, sad day for our region."

The Minister told Mackay he was concerned Westland shareholders did not get the full story from the co-op, and were unaware of more options.

"I'd like to think that ... more discussion could be had between Fonterra and Westland. The board has been very, closed-lipped and secretive about the whole thing."

"They've put one proposal to the farmers which in my view is not right. The shareholders should be demanding more information about what the alternatives were."

Read more: Death throes of a dairy co-operative: Westland Milk a loss of more than just money

The proposed sale to an overseas buyer contradicts the point of a co-operative and may have repercussions for the future, said O'Connor.

"There are serious concerns for the long-term issue of dairying in some areas of the West Coast, if you can't guarantee to have your milk picked up - that's why co-operatives were formed in the first place."

However, West Coaster Andy Thompson disagreed with the Minister, saying O'Connor had an "ideological bent," against the sale, and had campaigned against foreign ownership in the past.

"I think they'll find that 400 Westland farmers are probably pretty keen on it to be honest," he told Mackay.

Thompson predicted if the sale doesn't go ahead, that farmers would move to Fonterra and "I don't think Westland would be in existence."

"The tipping point for Westland to be non-competitive is very, very slight and I think this is a God send," said Thompson.

"I think the board has done a particularly good job to get a deal like this across the line."

Although farmers were disappointed to "lose control of their own destiny," Yili has "done very well with its suppliers," said Thompson.

"Westland farmers really need some help because the last five years, let's face it, have been pretty poor."