The Foreign Investment Review Board reviews all proposed investments by foreign government entities to make sure it is in the national interest but proposed investments by non-government foreigners are reviewed only if the property exceeds $244 million, or $1 billion for US investors.

The FIRB increased the threshold under an annual indexation policy from $231 million to $244 million at the beginning of the year.

Nationals leader Warren Truss said the threshold was moving in the wrong direction and required an urgent review.

“Lifting the threshold to $244 million before triggering FIRB analysis of foreign buyouts of individual farms is just ludicrous," Mr Truss said.

"We need to sensibly evaluate what the dramatic increase in foreign ownership means for farm-gate prices, food availability and for prices at the checkout. Clearly, with foreign interests buying out our farms and agribusinesses for their own food security, something has to give. The impacts must be fully reported and assessed."

But Assistant Treasurer Mark Arbib dismissed Mr Truss' comments as "another scare campaign by the Coalition", saying it was a scheduled indexation for private investors only.

Last week a government report revealed that more than 10 per cent of farmland is owned or part-owned by foreign companies, with a major cause being large land buy-ups by mining companies.

Mr Truss said better records of foreign ownership were needed. "No one farm is going to go for $244 million. But in the city, even the smallest suburban building block requires a referral to the FIRB. It just makes no sense," he said.

Senator Arbib said all applications from foreign governments or state-owned enterprises continued to be screened by the FIRB.

He said the government made agriculture policy decisions based on evidence, citing last week's report that found overseas investment improved food security and production.