The Overseas Investment Office (OIO) says it will consider prosecuting the woman who tried to buy the Crafar farms between 2008 and 2010 if she is not convicted in Hong Kong on fraud charges.
In a briefing to government ministers in August, the office said it believed May Wang broke the law governing overseas investments in land.
UBNZ Funds, UBNZ Assets and Natural Dairy bought four Crafar farms in February 2010 but neither they nor shareholder May Wang - a New Zealand citizen - got approval for the purchase.
The OIO says later in July they sought approval to buy the remaining 16 Crafar farms, then sought retrospective approval for the earlier purchase of the four farms.
It says UBNZ Funds and UBNZ Assets breached section 42 of the Overseas Investment Act by buying the farms without consent.
The OIO says May Wang breached the law by helping with the purchase.
May Wang and two others are facing charges brought by the Independent Commission Against Corruption (ICAC) in Hong Kong.
Land Information Minister Maurice Williamson says the Government is hopeful that if Ms Wang is convicted the courts will allow the four farms bought illegally to be sold on to New Zealand citizens or other eligible owners.
Mr Williamson told Radio New Zealand's Morning Report programme the Hong Kong case has been adjourned and it is not known when it will conclude.
He says Ms Wang will be charged in New Zealand if the prosecution in Hong Kong is unsuccessful.