In recent decades, many of the bloodiest conflicts in Africa and Asia have been fuelled by profits from the exploitation of natural resources, including diamonds, timber and minerals. Efforts are being stepped up to clamp down on the trade in these conflict resources.

• Millions have died in resource-fuelled wars since the late 1990s
• The Kimberley Process has reduced international trade in conflict diamonds
• Campaigners want legally enforceable rules for oil and mining companies

Trade in "blood diamonds" provided vital funding for warlords and rebels fighting civil wars in Angola, Sierra Leone and Liberia in the late 20th century. After this was exposed, pressure grew for an international mechanism to stop this trade, thereby cutting off cash for arms purchases and helping end conflicts.

The Kimberley Process - a scheme to certify the source of diamonds - was launched in 2003, and is credited with reducing the proportion of conflict diamonds in international trade to below 0.5 percent.

Most of the worst resource-fuelled wars in recent years have ended. But activists warn that, without greater efforts to make international trade more ethical, history could repeat itself.

Besides the Kimberley Process for diamonds, there are no formal global mechanisms governing trade in other conflict resources like timber, minerals and cocoa. Advocacy group Global Witness says a first step would be to reach an internationally agreed definition of what they are.

Campaigners also want legally binding rules to govern the conduct of multinational oil and mining companies, which they accuse of indirectly contributing to human rights abuses. Most major corporations have signed up to voluntary schemes, but critics say they lack teeth.