A Senate committee in Nigeria has released a document that purportedly details an offer of $1.5 billion from African telecommunications giant MTN to settle what is reportedly the largest fine in industry history.

South Africa-based MTN did not confirm or deny the settlement offer in a statement Friday. It said talks were continuing and urged shareholders "not to make decisions based on press reports."

Nigerian regulators last year fined MTN $3.9 billion for having 5.2 million active but unregistered SIM cards. The cards are considered a matter of national security as they can be used by extremists and criminals.

The communications committee of Nigeria's Senate on Thursday released the purported settlement offer, which included $250 million MTN agreed to pay in February as a "good faith" payment.