Telecom firms operating in Nigeria should not put their desire to make profits above security concerns, President Muhammadu Buhari said on Tuesday.
Nigeria has been pushing telecom companies to verify the identity of their subscribers amid fears that unregistered SIM cards were being used by criminal gangs in a country facing an insurgency by Islamic militant group Boko Haram.
MTN, Africa's largest mobile operator, has been fined $3.9 billion in Nigeria - its biggest market by sales - for failing to disconnect users of unregistered SIM cards.
The company, which makes about 37 percent of its revenue from Nigeria, is awaiting a ruling after launching a December court challenge over the fine, which equates to more than twice its annual average capital spending over the past five years.
"President Muhammadu Buhari ... urged telecommunication companies operating in Nigeria not to place their desire for huge profits above the security needs of the country," said spokesman Garba Shehu.
Buhari was speaking on Tuesday with members of the Nigerian community in Abu Dhabi, where he was attending an energy summit.
Buhari said telecom companies "must adhere to the rules and guidelines" of Nigeria's industry regulator by carrying out "the registration of all mobile phone users without exception" to help security agents, added Shehu.
The fine imposed on MTN by the Nigerian Communications Commission was reduced from $5.2 billion, which was based on a $1,000 penalty for each phone line.
On Tuesday MTN said its Nigerian business is likely to report about $955 million in annual profit after tax.