Researchers have released a new version of a database that records global land acquisitions by governments and private investors.
There has been growing concern that large purchases, often in Africa, were in effect "land grabs" by the rich.
But the Land Matrix Global Observatory says that many deals have been significantly exaggerated.
The database has been developed by a group of five international research centres.
For several years now, media reports of land acquisitions have highlighted the growing trend of private investors and national governments to secretly acquire land in poorer countries in order to secure supplies of food and other resources.
Campaigners have complained that these investments were often unjust, with the people living on the land being thrown off by the new owners.
But despite the concerns that many investors are buying to take advantage of high food prices, there has been very little clear information about the scale of the issue.
After being launched in beta mode last year, the Land Matrix Global Observatory now hopes to paint a more realistic picture of the number and impact of land purchases.
The database suggests that more than 46 million hectares of land have changed hands in 756 verified land deals. About half of all transactions take place in Africa, with many in Mozambique and Ethiopia.
But the researchers say that getting accurate information remains a significant challenge. They quote the example of the investment by Agri-SA, the South African national farmers' union, in land in Congo-Brazzaville.
Initial reports suggested that 10 million hectares were being purchased. In the end, a contract was actually signed for 80,000.
Much of the hype comes from investment companies trying to influence the market, the researchers say. They also believe the role of countries like China has been exaggerated.
"We see from the new data that the activities of China have been overestimated," Dr Ward Anseeuw, from the French research centre CIRAD, told BBC News.
"In the press you see China everywhere, but in the database there is not as much China as we think there is."
While the bulk of direct investment continues to come from western countries and companies, there are growing numbers of land purchases that are funded by national or regional governments. In Asia, over 80% of acquisitions are financed from within the region.
The researchers found that when land has been bought for agriculture, it was split equally between food and non-food crops. The team said there was no clear bias towards biofuel crops.
But apart from direct investment, the new database suggests there are some worrying trends emerging.
"What we are seeing is the development of other instruments that allow investors to be more invisible, such as contract farming or through bank control," said Dr Answeeuw.
"Instead of buying land through a foreign entity, they are buying stakes in local agribusiness that are controlling these lands."
While the researchers say that economic failures especially in Africa have made investors more cautious about where they put their money, the inflow of funds is still posing some significant challenges for indigenous peoples.
"In many cases, it is common land or community land that is under threat," said Michael Taylor from the International Land Coalition.
"If it is grazing land or land that local people use, they don't have any legal protection. It is on this land that we see the gravest of threats," he said.
The database now uses a wide number of data sources to help increase both accuracy and transparency. While those involved recognise its limitations they believe that it will promote good practice. Not all foreign direct investment is land-grabbing.
"If there is no investment in agriculture in Africa, it will not grow," said Dr Answeeuw.
"We need these investments; the public sector alone can't do this. We need the private sector to come in," he added.
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