African governments should avoid rushing into big land lease deals with foreign investors or risk deepening poverty and ramping up social tensions, an official at the UN's Food and Agriculture Office said.   

His comments follow an FAO study that looked at five countries in sub-Saharan Africa where at least 2.5 million hectares (6.2 million acres) of land have been allocated to large-scale investors since 2004.   

These and other deals are raising the hackles of rights groups who argue that the 'land grab' trend is reducing access to food for some of the world's poorest people.   

"Land has become a very visible and hot issue because many actors have realised that it is going to be scarce and a very valuable asset in the future," said Paul Mathieu, FAO's senior officer for climate, energy and tenure division.

"What is important is to make well-informed choices and not to rush quickly to allocate large tracts of land," he told Reuters in an interview last week after a regional briefing on land use.

Sub-Saharan governments eager to attract investment to spur economic activity have signed a flurry of land deals in recent years with resource-hungry investors, including from China, Brazil, and Malaysia.   

Mathieu said research carried out by the FAO and its partners showed that some 2,492,684 hectares -- an area about the size of Luxembourg -- had been allocated in large deals between 2004 and 2009 in Ethiopia, Ghana, Mali, Madagascar and Sudan alone.   

The largest single deal was 452,500 hectares for a biofuel project in Madagascar, he said.   

The FAO study did not take in Congo, where South African farmers have secured access to up to 10 million hectares of land to farm maize, soy beans, poultry and dairy cattle.   

"Land is at the core of the (African) economy and livelihoods, but also social, cultural and political aspects of life and there is strong social and emotional involvement in land issues," Mathieu said.   

Governments need to balance local land use needs against the need for foreign investment, he said. "This is and will be a tricky issue for governments to deal with as some external investors will say they've brought in a lot of capital and also want a lot of land. It is not easy but it is possible," he said.   

International anti-hunger group ActionAid called on the FAO on Monday to recommend curbs on big land deals in Africa and on food speculation.   

"An estimated 50 million hectares of fertile land -- an area double the size of the UK -- has (been) acquired overseas over the last few years by companies, investors and sovereign wealth funds, and very often to the detriment of poor people and local economies," it said in a statement.   

FAO statistics show that more than 73 percent of people in sub-Saharan Africa live in rural areas and that some 90 percent of agricultural production in the zone is carried out by smallholders on family farms. - Reuters