Financial secrecy by multi-national companies helps strip Africa of about 50-billion US dollars each year. Prominent social activists and anti-corruption watchdogs, that include Archbishop Desmond Tutu, Corruption Watch, and Transparency International, are jointly calling for the leaders of the Group of 20 biggest economies to stop that corruption. In an open letter to the leaders heading to Brisbane for the G20 Summit, the activists stress governments must make corruption by multi-national companies a priority. Sakina Kamwendo spoke to Corruption Watch Executive director David Lewis