New Zealand First is critical of Fonterra's sale of Tip Top to European company Froneri, calling overseas sales of New Zealand companies "an alarming trend".
Fonterra owned the ice cream company since 2001, but confirmed the $380 million sale today.
Mark Patterson of NZ First said the sale was disappointing.
"If we are to build a value-added future for our economy, keeping the ownership of brands like Tip Top in Kiwi hands is critical," Mr Patterson said.
He said Tip Top's returns will now "disappear overseas".
"The sale of Tip Top follows the foreign acquisition of other significant New Zealand companies capturing value-added opportunities.
"This is an alarming trend that New Zealand First will continue to oppose," Mr Patterson said.
Froneri is the third largest ice cream manufacturer in the world, selling ice cream brands in 20 countries.
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