The CEO of MTN, Africa's biggest telecommunications company, has resigned due to problems in Nigeria, where the company's subsidiary has been hit with a $5.2 billion fine.

The company, in a statement on Monday, quoted CEO Sifiso Dabengwa as saying: "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."

An interim leader of the telecommunications giant has been named while the company finds a new CEO.

The statement also said "Shareholders are advised to continue to exercise caution when dealing in the company's securities until a further announcement is made."

MTN Nigeria was fined for failing to meet a deadline to deactivate 5.2 million unregistered cellphone SIM cards.