South African mobile operator MTN Group said yesterday it was under United States investigation over its activities in Iran and Afghanistan, at a time of icy ties between Washington and Pretoria.

Africa’s biggest telecoms company is already facing court challenges in South Africa by Turkey’s Turkcell, which accuses it of winning the Iranian market through corruption.

In 2006, MTN was chosen over Turkcell to become the 49 percent minority shareholder in Iranian government-controlled mobile phone carrier Irancell.

MTN had been made aware of a US Department of Justice (DoJ) grand jury investigation relating to its former subsidiary in Afghanistan and Irancell, the company said in a statement.

“MTN is cooperating with the DoJ and voluntarily responding to requests for information,” said the statement accompanying the group’s financial results.

Grand juries typically decide whether or not to formally lay charges in a case and take it to trial.

The South African multinational is also facing a court case in the United States from US veterans wounded in Iraq and Afghanistan, as well as relatives of soldiers killed in action, the statement said.

“The plaintiffs’ complaints allege that MTN supported anti-American militias in Iraq and Afghanistan through its participation in Irancell,” it said.

MTN denied any wrongdoing and vowed to file a motion to dismiss the claims.

Relations between Pretoria and Washington have grown increasingly strained in recent months.

South Africa has drawn US criticism for its close ties with Russia, its decision to bring a genocide case against Israel at the International Court of Justice over the Gaza war, and for what President Donald Trump claims is the persecution of white farmers.

Trump has also slapped most South African exports with a 30-percent tariff — the highest in sub-Saharan Africa.