Olivier De Schutter, UN special rapporteur on the right to food, calls for consensus before talks this month on land governance, as commercial pressures mount

Governments should be wary of speculation and concentration of ownership when land rights are transferred to investors to "develop" farmland, a UN expert has warned before key UN negotiations on land governance.

"We must escape the mental cage that sees large-scale investments as the only way to develop agriculture and to ensure stability of supply for buyers," said the UN special rapporteur on the right to food, Olivier De Schutter, amid concern among civil society groups about "land grabs".

The recent surge in food prices has prompted investors and governments to focus on agriculture after decades of neglect. Attention has also focused on land deals in developing countries.

A report by Oxfam, published last month, identified 227m hectares (561m acres) of land – an area the size of north-west Europe – as having being reportedly sold, leased or licensed, largely in Africa and mostly to international investors in thousands of secretive deals since 2001. This compares with about 56m hectares identified by the World Bank earlier this year, again predominantly in Africa.

UN talks on land governance, which begin in Rome on 17 October, are the culmination of six years of negotiations involving governments, international organisations and civil society groups brought together under the UN's committee on food security (CFS). The session is expected to adopt the voluntary guidelines on responsible governance of tenure of land and other natural resources.

Urging participants to find a consensus, De Schutter said the world needs to establish general guidelines on land governance before adopting rules on land investment.

"Commercial pressures on land are rapidly growing. Biofuels, large-scale infrastructure projects, carbon-credit mechanisms, and speculation lead to rapid changes in land rights, creating new threats for vulnerable land users," he said.

"Climate change and population growth will exacerbate tensions within countries and between them. We need to establish general guidelines on land governance before we adopt rules on land investment. Harmful investments to the detriment of local populations – so-called land grabbing – can only be warded off if we first secure the underlying rights of farmers, herders and fisherfolk."

In its report Oxfam said many land deals in recent years often intended to grow crops for foreign food and biofuel markets, and can rightly be called land grabs as they violate human rights, particularly the equal rights of women; flout the principle of free, prior and informed consent of the affected land users, particularly indigenous peoples; ignore social, economic and environmental impacts; and avoid transparent contracts.

Much of the land grabbing has been driven by the expansion of sugar cane and oil palm for biofuel production, with thousands of evictions taking place in Uganda, Guatemala and Honduras.

Oxfam said most of the land deals in Ethiopia, Ghana, Mali, Mozambique, Senegal and Tanzania have been done to grow crops for export commodities, including cut flowers, as well as biofuels. Luca Chinotti, an Oxfam policy adviser in Rome, said one of the most critical issues at the Rome talks will be that all land deals should have the prior consent of communities. He also said the current draft of guidelines was "dramatically weak" in terms of women's rights.

The EU, particularly Germany, has strongly supported incorporation of international human rights standards into the guidelines throughout the negotiations. Brazil and Zimbabwe actively opposed the application of particular human rights standards, while the US and Canada came out strongly against the principle of consent, insisting any such notion be non-binding. Australia adopted a strongly unfettered market approach.

De Schutter said the voluntary guidelines could provide much-needed guidance about how conflicts over land use should be addressed. In May 2011, he issued a detailed set of proposals to ensure that these land guidelines are consistent with internationally accepted human rights standards, including the right to food, which have concrete implications for land issues.

"States have nothing to fear," De Schutter said. "There is much to gain in adopting guidelines that will improve the ability of governments to defuse land-related conflicts, in times of growing tensions over access to natural resources. The guidelines will also strengthen the bargaining position of states when negotiating with private investors. This could help avoid the current 'race to the bottom' in which countries compete in order to attract investors, dismantling any existing protection land users enjoy."