African mobile operator MTN says it will continue to dispute the $5.2bn fine imposed on it by the Nigerian Government, as its chief executive tendered his resignation last week.

As MTN CEO Sifiso Dabengwa resigned with immediate effect, he explained it was in the interest of the company and its shareholders.

Africa’s biggest mobile operator MTN Group was fined the equivalent of one fifth of Nigeria’s annual budget, after its Nigerian operation was found to have failed to manage its subscriber base properly.

The failure to cut off unregistered SIM cards had potentially wider repercussions than its own revenue streams however, with the BBC reporting that the Nigerian government imposed the fine after the kidnapping of a former finance minister, Chief Olu Falae, during which the kidnappers reportedly used an unregistered SIM card from MTN to demand a ransom.

MTN was given just two weeks to pay the penalty, which equates to twice the profits of the entire MTN Group, which operates in multiple African markets. The scale of the fine caused ratings agencies Moody’s and Fitch to lowered MTN’s credit rating.

With the 16 November deadline looming the company said it is negotiating to reduce the fine. The task of renegotiation falls to non-executive chairman Phuthuma Nhleko has stepped in as executive chairman for a maximum of six months while the company looks for a successor.

The fine is the equivalent of $80 per subscriber for MTN, which has 28.5 million subscribers in Nigeria, which is its biggest market. The MTN Group, whose next biggest markets are in Iran and South Africa, made $2.69bn in profit, after tax, last year.

Meanwhile Dadengwa, has given a statement explaining his position. “Due to the most unfortunate prevailing circumstances occurring at MTN Nigeria, I, in the interest of the company and its shareholders, have tendered my resignation with immediate effect,” said Mr Dabengwa.

Dabengwa, who had led the company as CEO since 2011, had risen through the ranks. He had been the company’s head of Nigerian operations before becoming the chief operating officer, a position in which he would have been familiar with the regulation of SIM card registration.

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