Ten leading aid agencies have called for a 'surge' in the humanitarian effort to help 10 million people at risk of acute hunger across the Sahel region of West and Central Africa. The centre of the crisis is Niger, where seven million people, almost half the population do not have enough food. A further two million people in Chad, and hundreds of thousands more in Mali, Mauritania, parts of Burkina Faso and the extreme north of Nigeria are also suffering as a result of the crisis.