European importers of minerals from conflict zones should be forced to certify their goods "blood-free", an influential group of EU lawmakers said on Tuesday, seeking to toughen a proposal to prevent the financing of warlords in Africa. Much of the gold, tantalum, tin and tungsten used in electronics and lighting is mined in areas of civil conflict in Africa and the European Commission, the EU executive, last year presented a plan for a voluntary certification scheme...But the European Parliament's trade committee wants to force smelters and refiners to certify their imports, voting 22 to 16 with two abstentions, to strengthen the draft law.