MTN Group on Thursday reported that its subscriber base had declined by 14.3 percent to 53.1 million in Nigeria in six months.
This follows a review of subscriber definitions and a decrease in gross connections as a result of new regulations that require all subscriber connections take place in permanent structures.
Despite this, MTN said total revenue from Nigeria operations increased by 10.8 percent, largely attributable to strong data revenue growth, which increased by 70.4 percent.
MTN said it continues to focus on growth in Nigeria despite a challenging macro-economic environment by focusing on reviewing and optimising both subscriber definitions and value-added services (VAS) subscriptions, placing some short-term pressure on subscriber net additions and VAS revenue.
Nigeria is MTN's largest market with at least a quarter of its 240 million subscribers.
MTN Nigeria is still reeling from the $1 billion fine imposed on it by the country's authorities for failing to deactivate more than five million unregistered SIM cards.
The biggest African mobile phone group was initially fined $5.2 billion but the fine was later reduced to $1 billion after negotions with the Nigerian government.
In March, MTN posted its first ever annual loss of R1.4 billion after the fine paid to the Nigerian government wiped a third off its earnings.
MTN also said it continued to make progress with preparations to list MTN Nigeria shares on the Nigerian Stock Exchange, anticipating completing this process in 2018 should market conditions permit.
MTN Group was releasing its interim results for the six months ended 30 June 2017.
Reported headline earnings per share (HEPS) were 217 cents compared to a 271 cents headline loss per share in the comparable period, impacted by the Nigerian regulatory fine of 474 cents. In the current period, the Nigerian regulatory fine interest unwind reduced HEPS by 24 cents.
Subscriber numbers in the period decreased by 3.6 percent to 231.8 million impacted by a decline in subscriber numbers in MTN Nigeria and MTN Ghana.
Group total revenue increased by 6.7 percent to R64.3 billion, supported by encouraging revenue growth in Nigeria, Uganda, Ghana and Ivory Coast. This was mainly a result of strong data and digital revenue growth in these markets.
MTN Cameroon reported a 4.2 percent decline in revenue, while total revenue growth in MTN South Africa increased by 1.6 percent.
Group president and chief executive, Rob Shuter, said they were seeing pleasing progress in key growth drivers of data and digital services against headwinds of challenging macro-economic conditions and foreign exchange currency pressures.
"We continue to strengthen our focus on operational excellence with our six strategic pillars integrated in our new Bright strategy," Shuter said.
"Our focus during the second half of the year will be to entrench our Bright strategy, complete our network investment programme and build medium-term financial KPIs and targets for the Bright strategy."
During the past six months, MTN management team undertook a thorough review of the group strategy and developed a clear growth plan for MTN that will be arranged under six strategic pillars (Bright), comprising: Best customer experience; Returns and efficiency focus; Ignite commercial performance; Growth through data and digital; Hearts and minds; and Technology excellence.