The complaint was filed in the United States District Court in the District of Columbia on Friday.

It alleges the firms violated the U.S. Anti-Terrorism Act by paying protection money to al Qaeda and the Taliban, thereby providing material support to known terrorist organizations.

It seeks damages on behalf of U.S. military members and civilians killed or wounded in Afghanistan between 2009 and 2017.

“MTN is reviewing the details of the report and is consulting its advisers but remains of the view that it conducts its business in a responsible and compliant manner in all its territories,” the company said in a statement.

The complaint follows investigations by a group of large Washington-based law firms and allege firms provided “material support” to known terrorists leading to numerous U.S. injuries and deaths, according to a statement by the law firms involved.

MTN spokeswoman Nompilo Morafo said the company could not yet respond directly to the specific allegations in the report as it was still going through the details.

“We cannot comment further than what we’ve said in the statement. We want a chance to review the allegations. We only received the suit on Friday and we’re still going through it. I also can’t confirm how long it’s going to take,” Morafo said.

MTN is Africa’s largest mobile operator and eighth biggest in the world with 243.7 million subscribers. It has previously faced scrutiny over its Iranian operations.

In February a former South African ambassador to Iran was arrested on charges that he took a bribe to help MTN win a $31.6 billion license to operate there.

The company has also faced costly disputes over unregistered SIM cards, tax and dividend repatriation in Nigeria.