Tech majors including Apple, Samsung and Sony have been accused of using cobalt mined by child labourers in Congo. Amnesty International also said the companies had failed to carry out basic checks on the source of the materials used in their products.

According to the report, This is what we die for: Human Rights Abuses in the Democratic Republic of the Congo power the global trade in cobalt, the London-based rights group said cobalt used in lithium-ion batteries that power many devices came from mines in which children as young as seven years work in dangerous condition.

The investigation

Bulk of the world's cobalt is sold by China's Huayou Cobalt and its subsidiary, Congo Dongfang Mining, to makers of component in China and South Korea. The component manufacturers then sell it to the battery-makers who supply it to companies such as Apple, Microsoft, Samsung, Sony, Daimler and Volkswagen.

The human rights group claims to have reached out to 16 multinational companies who were the customers of battery manufacturers who source minerals from Huayou Cobalt. While one company admitted the connection, four were unable to say whether they bought cobalt from the Democratic Republic of the Congo or Huayou Cobalt, Amnesty said. Another six companies said they were investigating the claims, whereas seven others denied sourcing cobalt from Huayou Cobalt. Amnesty said five companies that denied the claim were listed as customers of battery manufacturers who bought cobalt from Huayou.

"The glamorous shop displays and marketing of state-of-the-art technologies are a stark contrast to the children carrying bags of rocks, and miners in narrow manmade tunnels risking permanent lung damage," said Mark Dummett, business and human rights researcher at Amnesty International.

"Millions of people enjoy the benefits of new technologies but rarely ask how they are made. It is high time the big brands took some responsibility for the mining of the raw materials that make their lucrative products," he added.

Emmanuel Umpula, executive director of Afrewatch (Africa Resources Watch), said: "It is a major paradox of the digital era that some of the world's richest, most innovative companies are able to market incredibly sophisticated devices without being required to show where they source raw materials for their components."

Child labourers at mines

The DRC is said to produce about 50% of the world's total cobalt. Huayou Cobalt gets more than 40% of cobalt from DRC. Miners in the area face health issues and are prone to fatal accidents. About 80 miners died underground in southern DRC between September 2014 and December 2015, Amnesty said.

The child miners reportedly work up to 12 hours a day in the mine to get one or two dollars a day. According to Unicef, about 40,000 children worked in mines across southern DRC in 2014. Paul, a 14-year-old boy, told Amnesty's researchers: "I would spend 24 hours down in the tunnels. I arrived in the morning and would leave the following morning."

"Many of these multinationals say they have a zero tolerance policy for child labour. But this promise is not worth the paper it is written (on) when the companies are not investigating their suppliers. Their claim is simply not credible," said Dummett.

What the companies say

Apple in its response to the report told BBC, "Underage labour is never tolerated in our supply chain and we are proud to have led the industry in pioneering new safeguards." It also said the company conducts rigorous audits of the supply chain and suppliers face penalties in case they are found hiring underage workers.

Samsung said it had zero tolerance towards child labour and conducts regular audits of its supply chain. "If a violation of child labour is found, contracts with suppliers who use child labour will be immediately terminated," it said.

Sony said it was working with the "suppliers to address issues related to human rights and labour conditions at the production sites, as well as in the procurement of minerals and other raw materials."