Hong Kong (CNN Business) An international advocacy group has accused Apple, Google, Microsoft, Dell and Tesla of "knowingly benefiting from" the use of young children to mine cobalt in the Democratic Republic of Congo.

International Rights Advocates filed a federal class action against the five companies in Washington, D.C. on Sunday, where the group is based. The complaint claims that the firms "are knowingly benefiting from and aiding and abetting the cruel and brutal use of young children" to mine cobalt in extremely dangerous conditions.

The defendants have known for a "significant period of time" that Congo's mining sector "is dependent upon children," the complaint said, adding that cobalt mined in the region is listed as a good produced by child labor or forced labor by the US Department of Labor.

"Further, the horrors of the plight of these children has been widely reported in the media," the complaint said, citing reports about the cobalt pipeline published by the Washington Post, the Guardian and others.

Cobalt is a major component of lithium-ion batteries found in virtually every rechargeable electronic gadget. Two-thirds of the world's cobalt comes from Congo.

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