The World Health Organisation says a new polio outbreak in Sudan is linked to an ongoing vaccine-sparked epidemic in Chad " a week after the UN health agency declared the African continent free of the wild polio virus.

In a statement this week, WHO said two children in Sudan " one from South Darfur state and the other from Gedarif state, close to the border with Ethiopia and Eritrea " were paralysed in March and April. Both had been recently vaccinated against polio.