German carmaker Volkswagen has stopped buying mica from some suppliers in India, following a Thomson Reuters Foundation investigation that found child workers were dying in illegal, unregulated mines, a company official said.

A three-month investigation in the states of Bihar, Jharkhand, Rajasthan and Andhra Pradesh revealed that at least seven children were killed since June mining for mica, the mineral that puts a sparkle in makeup and car paint.

The investigation, coupled with a study of the industry by human rights group Terre des Hommes, prompted the world's top-selling carmaker to start investigations into its suppliers in India, VW spokeswoman Leslie Bothge said.

VW and its tier one, or direct, paint suppliers in India have put additional due diligence efforts in place to make sure the mica they are buying comes from legal mines where child labour is not used, Bothge said.

"Additional efforts were also undertaken at the second tier level," Bothge said in an e-mail in response to questions. "This has led to the temporary suspension of purchases on some supply chains until the due diligence is completed and respective measures have been put in place."

VW's paint suppliers are discussing the possibility of creating an "industry and multi-stakeholder platform" to address the issue and find solutions to avoid child labour in the mica supply chain, she said.

"To find sustainable solutions ... is not an easy task, and one that (will) also take some time," Bothge said.

India is one of the world's largest producers of mica, a silver-coloured, crystalline mineral that has gained prominence in recent years as an environmentally friendly material.

Labour rights campaigners estimate that up to 70 per cent of India's mica is produced in illegal mines falling into disrepair.

Other major global brands buying mica from India also vowed to beef up inspections of their suppliers for child labour after the investigation. These include Chinese pigment manufacturer Fujian Kuncai Material Technology, German drugmaker Merck KGaA and cosmetics maker L'Oreal.-Reuters