Kenya, which eradicated polio 25 years ago, has recorded 13 new cases of the virus in three months, health officials said Wednesday.
Public health director Shahnaaz Sharif said the new cases were reported in northern Turkana district which borders Ethiopia and war-torn Somalia.
The country issued an alert in February after a case of a rare wild polio was confirmed. The case sparked an emergency nationwide vaccination drive.
But Sharif blamed the latest outbreak on poor routine polio immunisation. He said the February case was suspected to have been imported from southern Sudan.
Kenya reported a first case of polio in more than two decades in 2006, confirmed to have orginated in Somalia.
Polio remains endemic in just four countries in the world, the hotbed being Nigeria, followed by India, Afghanistan, and Pakistan.
The International Red Cross last month warned that a polio outbreak now affects 15 African countries and could threaten efforts to eradicate the disease.
Some strains of polio can cause paralysis and even lead to death. The disease is transmitted via contaminated food, water and faeces.