EU lawmakers have narrowly backed tougher rules aimed at limiting the import of conflict minerals.
The European Parliament voted in favour of the draft law with 343 votes to 331.
Supporters say it should be more difficult for military groups to finance their activities by selling precious minerals, which are used in tech gadgets such as smartphones.
MEPs said any certification system should be mandatory, rather than voluntary as the European Commission had proposed.
That would mean companies would have to prove that all resources throughout their supply chain were ‘conflict-free’.
The US already has legally binding requirements, which focus on the Great Lakes region in Africa.
Parliamentarians will now negotiate with EU governments over what the final version of the law will look like.