The auto industry is becoming increasingly dependent on the DRC-dominated battery metal as it ramps up supply of electric vehicles, with Glencore expecting demand for the metal to increase 67% over the next three years.

IndustriALL said it went on a fact-finding mission to Glencore's Kamoto Copper Company and Mutanda mines in February after urgent requests from its affiliate TUMEC, which represents some workers at both mines.

The union said in its subsequent report that miners were only allowed 750ml of drinking water during a 12-hour shift, with food often expired and no decent places with shelter from the elements available to eat.

There were also no proper shower or ablution facilities at the mines, which was putting miners and their families at risk of contamination and occupational respiratory diseases.

"We are so filthy when we get home that we cannot hug our children," one worker was quoted as saying.

IndustriALL also said workers had to travel 42km to Glencore health facilities and there were large disparities in the salaries between white supervisors and Congolese assistants.

"The report outlines Glencore's disrespect for the collective bargaining agreement with TUMEC and its refusal to renegotiate. The mission also found that there has been no salary increase for workers in five years," IndustriALL said.

TUMEC was considering strike action over the disparity in wages, while IndustriALL has written to the Glencore CEO Ivan Glasenberg with a list of demands to redress the situation of workers at its mines in DRC. It also called on all car manufacturers to carry out due diligence on the sourcing of cobalt for the industry. 

IndustriALL general secretary Valter Sanches said customers expected EVs to be produced responsibly, but cobalt from Glencore was "anything but".

"We're not asking them to not buy from Glencore, we're asking them to pressure Glencore to live up to Glencore's own claims to produce responsibly and to respect workers' rights and the communities where it operates," he said.