Telecom group MTN has met Nigeria's Securities and Exchange Commission to discuss a possible initial public offering and how it wants to structure the share sale, the head of Nigeria's SEC has said.SEC director-general Mounir Gwarzo said MTN had discussed the possibility of issuing various classes of shares to targeted investor groups.He said the firm was looking at three different classes, which would be new in Nigeria.Gwarzo said the exchange commission was willing to support the share sale as long as it was within local laws and advised the telecom firm to ensure retail investors were protected.MTN is the largest mobile phone operator in Nigeria with 57million subscribers.The West African country accounts for about a third of its revenue.MTN - Africa's biggest mobile phone operator - has said it aims to list its Nigerian unit next year subject to market conditions, part of an agreement with the Nigerian government.In June, the telecom firm said it would list its local unit on the Nigerian Stock Exchange after agreeing to pay a reduced fine of $1.7-billion (about R25-billion) in a settlement with the Nigerian government over unregistered SIM cards.Gwarzo said the company was yet to submit a formal application for the share sale.MTN Nigeria has appointed Stanbic IBTC Capital, Standard Bank of South Africa and Standard Advisory London, and Citigroup Global Markets, as joint transaction advisers and global co-ordinators, with Stanbic acting as lead issuer...