The land of sub-Saharan Africa is blessed with resources. There's oil, gold, diamonds, timber, cobalt and more. But in some cases this wealth has turned out to be a curse. Impoverished communities have found themselves at odds with governments, rebel groups, foreign companies and mercenaries as they try to control a share of the riches beneath their feet. Competition for resources has in some cases triggered full-scale war.

An interesting map hangs on a wall at the United Nations headquarters in Bunia, in the eastern part of the Democratic Republic of Congo. Corene Crossin has seen it.

"It's an area rich in gold, and ivory and very, very valuable tropical timber," she said. "The U.N. has overlaid a map of where all of the major conflict spots are with where all of the natural resources can be found. So for example gold deposits are closely linked where battles have been fought."

Ms. Crossin researches Congo for Global Witness, based in Britain, which campaigns against abuses associated with natural resource exploitation. Historically, Congo has represented a worst-case scenario. During Belgian rule, if Congolese failed to bring back a certain quota of rubber from the forests their hands were chopped off.

More recently, up to three million people lost their lives in Congo as six nations and various rebel groups fought, in part, for gold, diamonds and other resources.

In Sierra Leone, rebels there severed the limbs of their victims in what became a war over diamonds. Other people were forced to mine the gems. The war in Angola was prolonged because of oil and diamonds. In Nigeria, violence has wracked the oil-rich Niger Delta for years as communities struggle for a share of the wealth.

Land rights in these countries and regions are virtually non-existent.

"With colonialism and neo-colonialism - our own people taking control of resources undemocratically - it has led to communities losing their land to governments and corporations," said Oronto Douglas, deputy director of a group called Environmental Rights Action in Nigeria.

Although Nigeria has abundant oil reserves, most of its people live in poverty. This dichotomy has fueled corruption and violence, violence stemming partly from environmental damage caused by oil exploration.

Traditional structures for land control and sharing resources have broken down across Africa in the past century. Now, a desperate sort of capitalism pervades the countryside in resource-rich countries such as Congo.

"Because there'd be a lot more money available for local people, for example, if they exploited gold that would ruin any kind incentive for people to continue with traditional economic activities like rural agricultural activities," said Corene Crossin of Global Witness. "So what you see is a complete breakdown of traditional economic activity and it's completely skewed now to natural resource exploitation."

To help avoid this, Mr. Douglas of Environmental Rights Action says local communities must have the right to control their resources.

"What needs to be done in Nigeria and all of Africa is the need to ensure that all citizens have their rights protected," he said. "Citizens in Nigeria and the rest of Africa don't have citizenship rights. The elite, a few people, grab power and decide for the majority. So what we're saying is there has to be the institutionalization of democracy."

In addition, Ms. Crossin says the international community must get involved in nations where foreign companies and other countries are involved in resource exploitation. She says this is especially true for Congo.

"Much more pressure needs to be placed on Rwanda, Uganda and Burundi to halt illegal exploitation of natural resources," she said. "There needs to be stronger border controls and also the international community can play a role in controlling the activities of western and multinational companies operating in the country, or buying the materials and helping the flow of arms through funding the purchase of gold, of diamonds, of timber."

The international community has imposed stricter controls on trafficking in conflict diamonds, and embargoes have been placed on timber. But until power and wealth are shared more equitably, the people in these resource-rich countries will remain squatters on their own land.