Some of the biggest technology firms in the United States have been accused in a lawsuit of complicity in the death and maiming of hundreds, if not thousands of African children who mine cobalt, a mineral vital to the production of the lithium-ion batteries in everything from smartphones to electric cars. The defendants named in the suit are Apple, Google parent company Alphabet, Microsoft, Dell and Tesla.

The lawsuit was filed Sunday in the U.S. District Court in Washington D.C. by the non-profit organization International Rights Advocates, on behalf of 13 anonymous plaintiffs from the Democratic Republic of Congo. The complaint accuses the tech giants of "knowingly benefiting from and aiding and abetting the cruel and brutal use of young children in Democratic Republic of Congo ('DRC') to mine cobalt."

The suit demands a trial by jury for the plaintiffs, who include maimed child miners and the families of others killed in the cobalt mines.

Human rights Lawyer Terry Collingsworth of International Rights Advocates told CBS News that his organization "traced the supply chain back from the mine where the children were either killed or maimed and have traced it back up to these companies."

The lawsuit calls for the companies to take responsibility for child miners in their supply chains, and change the way they source the metal.

Research by the United Nations Children's Fund (UNICEF) estimated that in 2012 there were about 40,000 children working in the DRC mines. More than half of the world's supply of cobalt comes from the DRC, and 20 percent of that is mined by hand, according to Darton Commodities Ltd., a London-based research company that specializes in cobalt.

Widespread reporting about the horrific conditions for children in DRC's cobalt mines has increased pressure on these companies for several years. But the lawsuit filed on Sunday, which was first reported by The Guardian, is the first legal action brought against the American companies.

Dell Technologies told CBS News in a statement that it's committed to "the responsible sourcing of minerals." The company denied it ever "knowingly sourced operations using any form of involuntary labor, fraudulent recruiting practices or child labor," and that it works with suppliers to manage sourcing programs responsibly. The company added that it is currently investigating the allegations, and that it has informed the Responsible Minerals Initiative as part of their grievance mechanism.

Apple told CBS News the company has "led the industry by establishing the strictest standards for our suppliers and are constantly working to raise the bar for ourselves, and the industry." The company added that since 2016, it has published a full list of cobalt refiners every year, all of which participate in third-party audits. "If a refiner is unable or unwilling to meet our standards, they will be removed from our supply chain," Apple said, adding that it removed six cobalt refiners in 2019.

A Google spokesperson called child labor and endangerment "unacceptable" in a statement to CBS News, and said the company's supplier code of conduct "strictly prohibits" it. "We are committed to sourcing all materials ethically and eliminating child mining in global supply chains," the spokesperson said. "As an active member of the Responsible Minerals Initiative, we work alongside our suppliers, other companies, and industry groups to drive efforts in and beyond the DRC."

The other defendants named in the case did not immediately respond to a request for comment.

Last year, CBS News correspondent Debora Patta traveled to the DRC. She and her team saw first-hand how gruelling and dangerous it is to extract cobalt from the ground — and they saw children doing it.

CBS News witnessed children barely 10 years old lugging heavy sacks of cobalt to be washed in rivers. Even those too young to work, including dust-covered infants clinging to their mothers and playing on the dirty ground, spent much of the day breathing in toxic fumes, Patta found.

Officials in DRC denied there was child labor, but for the CBS News crew, it was plain to see. Whenever a camera or security person or policeman appeared, the children were chased away. Our sources in the DRC say conditions for the children have not improved since we visited the country.

On that visit, the CBS News team met Ziki Swaze, an 11-year-old orphan who worked in the mines who dreamed of going to school. "CBS This Morning" viewers were so moved by Ziki's plight that they connected with the Good Shepherd International Foundation. Enough money was raised to send not only Ziki, but also his three siblings, Ruth, Emerson and Simitri, to school.

"I would see the other kids going to school and I would look at them," Ziki said, "but today I feel the happiness they feel and I am now like them."

Last year, CBS News asked a wide range of companies, including Apple, Microsoft, Tesla, and Dell, whether child-mined cobalt was being used in their products. All of the firms acknowledged problems with the supply chain, but said they required their suppliers to follow responsible sourcing guidelines.

CBS News' investigation showed, however, how complicated it is to trace child-mined cobalt in the global supply chain. Patta and her team followed the mineral as it left the mines, piled high on every mode of transport available. The unlabeled sacks were mixed up even as they left the mines, making it impossible to know who had mined the mineral inside.

The child-mined cobalt was brought to a large market where it was bought by a Chinese company for extremely low prices.

CBS News wanted to see whether there was any attempt to check at the market whether the cobalt had been mined by children, so Patta's team went back later, with a hidden camera. When they offered to sell a truckload of cobalt, nobody asked who mined the mineral, only what the quality was.

The lawsuit filed by International Rights Advocates (IRAdvocates) on Sunday claims the children on behalf of whom the plaintiffs have sued worked illegally at DRC mines owned by British company Glencore and others. The filing says cobalt from the Glencore mines is sold to a metal and mineral trading firm in Belgium called Umicore, which sells refined cobalt to the named defendant corporations in the U.S. The court document said children were also working at mines owned by Chinese company Zhejiang Huayou Cobalt, which supplies at least three of the named corporations.

In a statement to The Guardian, the British company Glencore said it "does not tolerate any form of child, forced, or compulsory labor."

IRAdvocates notes the claims by Apple and other firms of efforts to ensure their cobalt comes only from sustainable, legal sources, but says those efforts are insufficient, in part because they can rely on reporting from within the local mining communities.

"Until they are forced to do better, Apple and the other companies are relying on largely illiterate, desperately poor, and exceedingly vulnerable people to figure out Apple's complaint mechanism and report supply chain violations when they certainly cannot afford personal computers or iPhones and they do not have internet or cell phone access to connect to the outside world within the context of a violent regime that does not tolerate dissent and an unregulated industry that could retaliate with impunity against any whistleblowers," the court filing states.

Editor's note: This story was updated at 5:14 p.m. to include a response from Google.