Rising food prices could spread social unrest across Africa after triggering riots in Niger, Senegal, Cameroon and Burkina Faso, African ministers and senior agriculture diplomats have warned. Kanayo Nwanze, the vice-president of the United Nations' International Fund for Agriculture, told a conference in Ethiopia that food riots could become a common feature, particularly after the price of rice has doubled in three months. "The social unrest we have seen in places such as Burkina Faso, Senegal or Cameroon may become common in other places in Africa," Mr Nwanze said.