(Telecompaper) MTN Group CEO Sifiso Dabengwa has resigned with immediate effect. A statement from the company said Phuthuma Nhleko, the current non-executive chairman has agreed to act as executive chairman for up to six months while the company identifies a successor for Dabengwa. In his resignation, Dabengwa said "due to the most unfortunate prevailing circumstances occurring at MTN Nigeria," he has in the interest of the company and its shareholders tendered his resignation with immediate effect. Nhleko was CEO until March 2011 when Dabengwa took over. Alan van Biljon will continue to serve as the Lead Independent Director on the MTN board of directors whilst Nhleko takes over executive responsibility.