Professor Pinstrup-Andersen, who is in Australia for an agriculture and economics conference, said governments in poor developing countries in Africa and Asia are leasing land to foreign governments and companies, often in secretive deals, kicking off small farmers in the process because there is no formal land title.

Foreign investors then develop the land and export food back home, doing nothing to improve food security in these nations.

Professor Pinstrup-Andersen told The Age that Australia and other developed countries must build better international agreements to stop the exploitation.

''What Australia and other developed countries can do, is try to push for some international agreements as to how these land transactions take place,'' he said. ''We have rules for trade, they don't always work very well, but we have nothing for land acquisition.''

He said Australia must also continue to be a stronger exporter, particularly with wheat, to help stabilise world food prices and it must not waste agricultural land to produce biofuels.

''I think the time has come to stop using the resources for biofuel production,'' he said. ''If we have to produce biofuels let's try to find resources that don't compete with food production.''

The Department of Agriculture says Australia is a significant net exporter of food, with an export surplus of $14.2 billion over food imports in 2009-10 (the most recent statistics available).

The value of food exports was $24.3 billion in 2009-10, with imports valued at $10.1 billion.

He said Australia could help poor nations avoid exploitation by keeping up liberalised trade for major commodities.

The Danish economist said the biggest challenge for most countries, including Australia, was weather fluctuations and extreme weather events, including drought and floods - which he says are caused by climate change - that would continue to affect food production and prices.