Mr Peters' primary targets for criticism have been Chinese investment in New Zealand and Chinese immigration to this country.
He said yesterday that the sale of valuable land to any country was absurd because New Zealand was the world's leading agricultural nation, and other countries could not add value to it.
"In the case of these purchases, there is no new employment, there is no new investment, frankly it's a corporate raid. It's not a long-term stake in the country."
The OIO said that it was satisfied that Harvard's investment would have "substantial and identifiable benefit" to New Zealand, in the form of job creation, greater productivity, and increased investment in developing the land.
Mr Peters was concerned that ministers had no record of the extent of foreign ownership of forestry, farmland or property interests.
Asked whether he opposed American filmmaker James Cameron's purchase of close to 1300ha in Wairarapa, he said Mr Cameron's case was different because the Titanic director intended to live in New Zealand.
"If people come to live in this country and commit themselves to the economic and social future of New Zealand, that's a different matter. If it's absenteeism and foreign interests from abroad with no intention of doing anything in this country other than to exploit its resources, that's something else."
Harvard's investment arm planned to upgrade the dairy farm and use it in conjunction with the other two farms.
The Ivy-League institute is the world's wealthiest university with a $31 billion investment portfolio - larger than the New Zealand Superannuation Fund which stands at $22 billion.
It bought the cutting rights for the Kaingaroa forest in 2004, reportedly for around $650 million, but has since sold some of its stake.
Political debate about overseas ownership of farmland has been heightened by the purchase of 16 dairy farms, a total of 8000ha, by Chinese company Shanghai Pengxin last year.
In the past month, the OIO also approved land purchases and business investments from Canadian, Chinese, British and Australian investors.
Harvard's footprint
• 1700ha Big Sky farm, Otago ($34 million)
• 600ha Helenslea farm, Otago ($28 million)
• 1300ha farm near Maniototo (n/a)
• Cutting rights for 162,000ha of Kaingaroa Forest ($650 million)