The airport’s plans came to light after Treasury made public a list of titles of advice to ministers from November last year.
One of those was a report to Finance Minister Nicola Willis and State Owned Enterprises Minister Simeon Brown entitled "Dunedin Airport Land Acquisition".
Dunedin Airport chief executive Daniel De Bono said he could not comment on the land acquisition for the time being.
However, he said it had "nothing to [do] with a runway extension".
Dunedin International Airport Ltd is a council-controlled organisation, owned 50% by the Crown and 50% by Dunedin City Holdings Ltd.
Its website states that land adjacent to the airport "held for possible expansion" was being used for dairy farming in partnership with a sharemilker.
A small residential housing estate adjacent to the airport provided rental income.
Mainland Air chief executive Phil Kean said he had heard Dunedin Airport was in negotiations to buy another section of farmland on the western side of the airport.
There are two sections of farmland adjacent to the west of the airport, 33ha and 39ha valued at $1.65million and $1.68m respectively.
The Dunedin City Council’s rating information database confirmed the airport owned a 64ha section of farmland used for dairying, valued at $3.21m.
