Labour is calling for stronger foreign investment rules after the Court of Appeal rejected an attempt by Sir Michael Fay and two Maori trusts to block the sale of the Crafar farms.
The Chinese company that bought them, Shanghai Pengxin, says it can now go ahead with its programme of improvements on the 16 dairy farms.
Labour leader David Shearer says they should have stayed in Kiwi hands.
"Farming is the soul of our heartland but National is happy to see farms priced out of locals' reach and the profits flow offshore," he said.
"Overseas investment needs to demonstrate it will bring in new ideas, create new jobs and significantly improve the local economy - we're not against foreign investment but Shanghai Pengxin won't bring anything new to the table."
Labour has drafted legislation to strengthen foreign investment rules.
"It would substantially limit the discretion of the minister to consent to the sale of rural land to overseas buyers," Mr Shearer said.
Sir Michael and the trusts had sought a judicial review of the sale, which was approved by ministers.
Shanghai Pengxin reportedly offered $210 million for the farms, while Sir Michael and his partners offered $171.5m.
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