Los Mineros labor union alleges Industrias Peñoles violated workers’ freedom of association and collective bargaining rights at the company's mine in Zacazonapan.
SQM and Australia's richest person Gina Rinehart's Hancock Prospecting, already Azure's two largest shareholders, teamed up in December to buy the lithium developer.
In December, Nippon agreed to buy US Steel for roughly $15 billion but the deal faces an uphill battle to approval amid bipartisan opposition in a US election year.
