The European Union (EU) is set to adopt a new law on Wednesday to make it more difficult for armed groups to finance their activities through the sale of conflict minerals.

Under the draft law, first introduced last year, companies operating close to areas of civil conflict in Africa and elsewhere will have to prove their supply of tin, tantalum, tungsten, and gold are from conflict-free sources.

"Proof of origin of the raw materials will be crucial but according to the EU draft it could be on a voluntary basis," reports Deutsche Welle.

In the United States, the Dodd-Frank Act already forces US stock exchange-listed companies to disclose the use of minerals from an African conflict zone in their supply chains.

But Dodd-Frank, in place since 2010, has not been a complete success:

"The experience with the Dodd-Frank Act shows that for many companies to provide evidence of origin for the raw materials cannot be achieved. The production chains are too long and too complicated,” said Matthias Wachter, head of security and resources at the Federation of German Industries (BDI). He thinks this should be on a voluntary basis.

"But according to Andreas Meinhart, a researcher at the Freiburg Institute for Applied Ecology and co-author of a study that examines the impact of the Dodd-Frank Act on behalf of the BDI, the law has meant that in order for many US companies to comply with the law, they have had to completely shun commodities from the Great lakes region and the DRC.

"A boycott of Congolese raw materials could deprive thousands of people's of their livelihood. Critics warn of the risk that the unemployed young men will have no other alternative but to join armed groups."