A customer uses a cellphone beside an MTN Connect Point in Lagos, Nigeria. File picture: George Osodi

Johannesburg - South Africa's MTN Group may list its Nigerian unit on the stock exchange in Lagos once it has resolved a disputed $3.9 billion fine with authorities in the Western African nation, its executive chairman said on Thursday.

MTN also said it has set aside R9.3 billion ($600 million) to cover a potential settlement of a fine imposed by Nigerian authorities last year for failing to cut of unregistered SIM card users.

However, this amount may not be the final amount it pays, its executive chairman said on Thursday.

"Like most provisions, it's based on prevailing circumstances. It is not a number of finality," Phuthuma Nhleko told reporters.

Africa's biggest wireless phone company is in talks with Nigerian authorities to reduce a $3.9 billion fine imposed last year for failing to cut off unregistered SIM card users.

Read also: MTN cuts dividend

MTN posted a more than 50 percent drop in annual profit on Thursday.

Shares in the mobile company rose more than 9 percent to R149 by 0845 GMT.