A critic of foreign land sales is not happy with the way the Overseas Investment Office is monitoring conditions on sensitive land sales it's approved.

The agency's faced political pressure from opposition parties this year, accused of rubber stamping land sales and not enforcing conditions imposed on those sales.

Information released by the Overseas Investment Office, under the Official Information Act, shows its monitoring of sales generally involves the consent holder reporting back on how its complying with the land sale conditions.

New Zealand First leader Winston Peters said that approach might as well have been written in the 1950s, in the pre-computerisation era.

"Because in this computerised age, such an answer is woefully inadequate to the extent of being irresponsible."

Mr Peters said monitoring is a generous phrase to use, when in fact it's largely voluntary on the part of the applicants.

In response to an Official Information Act request the OIO says between 2006 and 2017 it's required 12 consent holders to dispose of sensitive land.

Mr Peters said that tells you, given the common knowledge of non-compliance, how loose the whole operation is.

Eight of the consent holders have been named including; Jian Xin Jia, US based company Fireseed LLC, UK firm PH2 Developments, Russian billionaire Mikhail Khimich, Danish national Kirsten Biltoft, Belgian owned firm Nirvana Capital, and Silver Fern International Travel and Trade Limited - a China based consortium.

The other four have had their details withheld; one because it's still under investigation, and three others for privacy and commercial reasons.

Meanwhile there are another five cases where the OIO says investors voluntarily decided to dispose of their properties before being required to by the agency.

Information released reveals over the last five years the Overseas Investment Office has consented between 102 and 133 land transactions annually.

The same data shows the agency has run between 500 and 700 monitoring activities annually, and is running checks on conditions of consent for up to five years.