From Prof Jeffrey D. Sachs.

Sir, For the record, my Columbia University colleague Glenn Hubbard misrepresents my views regarding aid and African development ("Only local business can end global poverty", July 24). Bono, Bill Gates and I do not "champion the current aid system".

All of us have helped to create innovations to the aid system, such as the Global Fund to Fight Aids, TB and Malaria, the Alliance for a Green Revolution in Africa, the Global Alliance for Vaccines and Immunisations, and the recent Group of Eight commitment to smallholder farmers. We champion a mix of public and private efforts.

I am glad that Prof Hubbard comes out in favour of Marshall-plan style aid, but with some serious caveats. First, there is no novelty to his endorsement of private-sector-led development, except for the fact that such a focus makes sense for certain challenges, such as agribusiness development, but not for others, such as the control of Aids, TB, malaria and polio among impoverished individuals. More generally, Prof Hubbard mistakenly conflates the conditions of post-war Europe in the Marshall plan days with those of present-day Africa. He also brushes over the fact that Europe's post-war boom involved active social programmes alongside business development.

Jeffrey D. Sachs,

Columbia University,

New York, NY, US