The rivalry between Samsung Electronics and Apple Inc. was brought to the fore again after an international organization slammed both tech giants for using suppliers that employ child labor and may harm the environment.

According to Friends of the Earth, an international environmental group, Apple has remained silent on the issue of using tin mined from Indonesia, whereas Samsung has responded by saying it will address the issue as soon as it can.

“Apple has refused to answer its own customers’ questions about Bangka ― even though Apple almost certainly uses the island’s tin,” the group said.

Bangka is the Indonesian island where the tin comes from.

Friends of the Earth claims that unregulated tin mining on Bangka is linked to child labor and is possibly a cause of extensive environmental damage to tropical forests and coral reefs there.

The practice also allegedly kills 150 miners a year, according to an investigation jointly conducted by the group and the U.K.’s Guardian newspaper.

Samsung has admitted to using Bangka tin and said in an email sent to the group that it was committed to addressing the problem.

“While we do not have a direct relationship with tin suppliers from Bangka Island, we do know that some of the tin that we use for manufacturing our products does originate from this area,” Samsung wrote.

The Korean company also said it is contacting suppliers, industrial bodies and government to search for solutions.

“It’s great Samsung has taken an industry lead by tracking its supply chains all the way to Indonesia’s tin mines and committing to taking responsibility for helping tackle the devastating impact that mining tin for electronics has on people and the environment,” Craig Bennett, the group’s director of policy and campaigns, said in a statement.

“Rival Apple is already playing catch-up on the high street in terms of smartphone sales ― it’s time it followed Samsung’s lead by coming clean about its whole supply chains too,” he said.

Tin is a vital component in all electronic gadgets, including smartphones and tablets, for the solder that holds together resistors, transistors and circuit boards.

International organizations have grown increasingly concerned about such issues, including the exploitation of child labor and the environmental damage caused by commercial activity.

Last year, Friends of the Earth launched an online petition urging Apple and Samsung to stop using the tin. When there was no response from Apple, the group issued another petition signed by some 20,000 people as of Sunday.

The group previously launched a campaign called “Make It Better” backed by some 15,000 individuals in November last year, calling for new rules for the top smartphone makers and transparency on supply chains.

By Park Han-na (hnpark@heraldcorp.com)