Telecoms giant MTN on Monday said it was reviewing allegations raised in a US complaint that accuses several firms of paying protection money to militant Islamist groups in Afghanistan.

The complaint was filed in the US District Court for the District of Columbia in Washington on Friday.

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

It seeks damages on behalf of US 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," said the company in a statement.

UK security services company G4S, which was also named in the lawsuit, declined to comment.

The complaint follows investigations by a group of large Washington-based law firms and alleges that firms provided "material support" to known terrorists, leading to numerous US injuries and deaths, according to a statement by the law firms involved.

MTN spokesperson 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," said Morafo.

MTN is Africa's largest mobile operator and the 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 $31.6bn (R445.65bn) licence to operate there.

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