(Bloomberg) -- Shares in MTN Group Ltd. fell the most in more than two months after Africa’s largest wireless carrier said it’s reviewing a demand by a Nigerian tribunal for unpaid taxes. 

The Lagos-based Tax Appeal Tribunal ordered MTN to pay $72.6 million, according to documents seen by Bloomberg and verified by two government officials. Calls to the tribunal weren’t answered when Bloomberg sought comment.

“We are reviewing the decision of the tribunal and will comment on this when we release our trading statement” on Oct. 27, the company said Wednesday in response to questions. 

MTN shares dropped as much as 4.1% in Johannesburg Thursday, the most intraday since Aug. 18. They were 3.7% lower by 11:59 a.m. local time and at their weakest level since June 2021.

Africa’s biggest mobile operators are increasingly being caught up in tax disputes on the continent. MTN has a history of impasses in Nigeria and was victorious in a conflict in the West African nation in 2020, when the government dropped a $2 billion claim for back taxes after a 16-month battle. 

More recently, Ghana had to abandon a $773 million back-tax bill against MTN that the company disputed. In the Democratic Republic of Congo, its cross-town rival Vodacom Group Ltd. has been embroiled in a tax demand that led the government to seal parts of its offices and freeze its bank accounts.

Last week, six telecoms chief executives — including MTN’s Ralph Mupita and Vodacom’s Shameel Joosub — urged African leaders and policymakers to “rationalize” tax for the mobile industry through the development of targeted fiscal policy reforms, such as the removal of tax on low-cost smart-phones and sector-specific tax, according to an agreement signed in Rwanda.

Nigeria is Johannesburg-based MTN’s biggest market by subscribers and the Lagos-listed unit MTN Nigeria Communications Ltd. contributes more than a third of the group’s total revenue.

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