ABUJA, Nov 4 (Reuters) - MTN Nigeria plans to launch a one-month public offer of 575 million shares to retail and institutional investors from this month, after it listed on the local bourse two years ago, the telecoms firm said on Thursday. The share sale will take place via bookbuilding for institutional investors and at a fixed price to retail investors, the local unit of South Africa’s MTN said. (Reporting by Chijioke Ohuocha; Editing by Jan Harvey)