The United Nations is drawing up a "code of conduct" in an effort to slow what's been described as a new scramble for Africa, while agriculture experts are calling for a new global watchdog and aid agencies are appealing for a moratorium on new deals.

Countries including the Gulf States, China, South Korea and a host of private investors and sovereign wealth funds have provoked serious concerns internationally with a string of aggressive and often secretive deals for large tracts of arable land on the world's hungriest continent.

David Hallam, the deputy director of the trade and markets division at the UN's Food and Agriculture Organisation (FAO), and one of the experts drafting the code, said yesterday that the "principles are agreed" and he expected leaders to make a joint statement at a summit in Rome in a fortnight's time. "It's going to bring these deals into focus and make people think about what's going on," he told The Independent.

According to FAO figures the recent wave of land acquisitions is equivalent to one-tenth of the entire area already farmed in Africa, or twice the arable land in Germany.

The code is expected to try and break the secrecy surrounding these deals and ensure locals' rights are not being trampled by big corporations or governments and that Africans' food security is not further threatened. "In the worst cases it's fair to say we are looking at neo-colonialism," said Dr Hallam.

In the last year Saudi Arabia

has added to huge holdings in Sudan with a $100 million deal for land in famine stricken Ethiopia; Qatar has begun acquiring 40,000 hectares in Kenya's Tana River Delta to grow fruit and vegetables despite a drought that sees the UN feeding four million Kenyans; China has added to its huge holdings in Zimbabwe and Algeria; and Egypt has leased 2 million acres of land from Uganda to grow corn and wheat.

The deal that really brought the phenomenon to the surface was the Madagascar government's decision to lease 1.3 million hectares, or half the island's arable land, to the South Korean giants Daewoo for 99 years for biofuel plantations. When it was revealed that Daewoo would pay nothing for the land and would instead barter it for infrastructure projects, president Marc Ravalomanana's administration became the first to be toppled over "land grabbing". The deal has been scrapped.

The scramble has its roots in last year's food crisis, which saw a huge spike in the price of staples and food protectionism, where countries slapped export bans on rice and other foodstuffs. Food was not only more expensive, it was unavailable. Then came the oil price rises. "Oil-rich and water-poor countries suddenly became interested in securing their long-term food supplies," said Ruth Meinzen-Dick, senior research fellow at the International Food Policy Research Institute (IFPRI) in Washington.

"Many of these deals were quite secretive and there was no clear benefit for the people living in these areas."

Added to these factors was the historic switch from food to fuel, driven by US subsidies for corn-based ethanol and hasty moves by the EU to set targets to switch from fossil fuels to bio-fuels which have since been reversed.

The IFPRI is calling for a watchdog "with teeth" to ensure that there is "informed consent" in poorer countries where land is being leased, as well as respect for African customary law, which is supposed to protect the traditional rights of smallholders.

Meinzen-Dick advocates a system that would ensure that in times of shortage there would be restrictions on the amount of food exported from foreign-owned land.

The irony is that the current trend could be a win-win situation as everyone is agreed that Africa is in dire need of investment: foreign aid and domestic spending on agriculture has dipped alarmingly in the last two decades.

The London-based International Institute for Environment and Development rejects the "land grab" analysis as too "simplistic". In a recent report the think-tank argued that there can be an upside if the investments are structured to create "new opportunities".

The report does warn that too much of the land being signed away is "high value" and that African governments are pushing through deals under the pretence that common land is "unused".

Speaking at an FAO event in Washington earlier this year Chido Makunike, a Zimbabwean agricultural consultant, explained: "In Africa, far from being perceived as a mere economic resource land has cultural, sentimental, and political meanings, and represents one of the strongest symbols of dispossession during the colonial era."