MTN said it was reviewing the details of a report claiming that it violated the US Anti-Terrorism Act by supporting the Taliban in Afghanistan.
A complaint has been filed in the district of Columbia, claiming that several western businesses were involved.
This was by allegedly making payments to ensure the protection of their infrastructure.
The defendants named in the complaint are six different groups, one of which is MTN and some of its subsidiary companies, including MTN Afghanistan.
The claim has been filed on behalf of civilians and the families of American service members, who were killed or wounded in Afghanistan between 2009 and 2017.
MTN said it was consulting its advisers but remains of the view that it conducts its business in a responsible and compliant manner in all its territories.
It said it would defend its position where necessary.