MTN Nigeria is reportedly under investigation by the Nigerian Economic and Financial Crimes Commission over its recent listing in Nigeria. Reuters reports that despite the investigation, MTN said it "has not been accused of any wrongdoing" by the Nigerian financial crimes agency.

The listing of MTN Nigeria on 16 May made it the second-largest firm on the Nigerian Stock Exchange (NSE), and since then its share price has risen from 90 naira to 140 naira, giving the company a market capitalisation of 2.8 trillion naira ($7.8 billion).

The Lagos listing is happening in two parts, the first was to allow existing Nigerian investors, who previously traded over-the-counter, to now trade publicly on the NSE. At a still unknown future date, MTN will also sell more shares to the public, as it reportedly looks to increase local ownership of MTN Nigeria from just over 19% currently, to around 35%.

"We received all regulatory approvals required to list our shares," MTN Nigeria said in a statement. "We are co-operating fully with the authorities."

According to Bloomberg the Economic and Financial Crimes Commission has requested certain information and documentation regarding the Nigerian listing of the South African telecoms giant. Bloomberg claims the company's Lagos head office was raided by the financial crime agency on Friday in connection with the probe.

MTN has faced a string of legal woes and accusations by various Nigerian authorities over the past few years which has weighed on the telco's reputation and its shares on the Johannesburg Stock Exchange.

The listing on the Nigerian Stock Exchange was itself a condition of a settlement reached with the telecommunications regulator in 2016 after the group failed to meet a deadline to disconnect 5.1 million unregistered SIM cards in the West African country.

The company also still needs to sort out a $2 billion tax row with Nigeria's attorney general. A court case between MTN and the attorney general over the matter was first scheduled for 8 November 2018 but has since been postponed a number of times and is now set for 26 June.

The Central Bank of Nigeria in August 2018 demanded MTN repatriate $8.1 billion to Nigeria, which the bank said the company had sent abroad in breach of foreign exchange regulations, which MTN denied. In December 2018, MTN agreed to make an almost $53 million payment to resolve the dispute, without admission of liability.

MTN Nigeria accounts for a third of the Johannesburg-based group's core profit and the telco had 60.3 million subscribers in Nigeria at the end of March 2019.