Four new cases of poliomyelitis have been reported in Damaturu, Karasuwa and Gulani Local Government Areas (LGAs) in Yobe.
The World Health Organisation (WHO) Coordinator in the state, Dr Isa Adamu, told the News Agency of Nigeria (NAN) on Wednesday that "the two cases reported in Damaturu were in areas with high security risk.
"We can not risk sending anybody to that area because of the high security challenge in that location."
Isa expressed the fear that except there was improvement in the security situation and immunisation conducted, there might be more new cases of polio in the state.
The coordinator noted that about 80 rounds of immunisation had been carried out across the state from 1998 to date.
He commended the Yobe Government for prompt payment of its counterpart funds towards the eradication of polio in the State.