Apple has temporarily stopped buying cobalt mined by hand in Congo, while it continues to deal with problems relating to child labour and harsh work conditions.

A Washington Post investigation last year detailed abuses in Congo's artisanal cobalt supply chain, showing how miners — including children — laboured in hazardous, even deadly, conditions. Amnesty International and other human rights groups also have alleged problems. Earlier this week, British broadcaster Sky News published an investigation that alleged continued problems in the cobalt supply chain.

The Post connected this troubling trade to Zhejiang Huayou Cobalt Company, a Chinese firm that is the largest buyer of artisanal cobalt in Congo and whose minerals are used in Apple products.

Last year, Apple pledged to clean up its cobalt supply chain, but the technology giant said it wanted to avoid hurting the Congolese miners by cutting them off. Mining provides vital income for hundreds of thousands of people in what is one of the world's poorest countries.

Now, Apple says it has stopped — for now — buying cobalt from artisanal mines.

"We have been working with Huayou on a program that will verify individual artisanal mines, according to our standards," Apple said in a statement, "and these mines will re-enter our supply chain when we are confident that the appropriate protections are in place."

Cobalt is essential for the lithium-ion batteries found in laptops and smartphones, such as the iPhone. Sixty percent of the world's cobalt supply comes from Congo.

Apple has said it intends this year to begin scrutinising its cobalt suppliers like it does its "conflict mineral" suppliers — the tin, tungsten, tantalum and gold from Congo that companies are required by securities law to attempt to certify does not come from militia-controlled mines. Apple said it plans to publish a list of the cobalt smelters, just as it does for its conflict mineral smelters.

Sky News reported that children continued to be employed in the cobalt mining that feeds into Apple's supply chain. The report was centred on the former Katanga province of Congo, where Huayou Cobalt operates, although the Sky News report does not specify the locations.

A Huayou Cobalt spokesman told The Post this week that it was investigating the allegations made in Sky News story and had asked the broadcaster for more details.

Apple said it continues to work with local groups in Congo to improve conditions for workers and stop child labor. And once those conditions are addressed, Apple said, it hopes to resume buying artisanal cobalt.

The Washington Post