ABUJA (AFP) -- Nigeria on Tuesday asked international donor agencies and the health sector to urgently analyze a polio vaccine being used in the country after allegations by Muslims leaders that it was unsafe.

Analysis was necessary "to remove all doubts as to the genuineness of the polio vaccines", Vice-President Atiku Abubakar said in a statement.

The World Health Organization (WHO) warned last week that a spate of polio cases in Nigeria, Africa's most populous country, was threatening to spread and undo successful immunization schemes in neighboring countries.

At least three northern Nigerian states have suspended polio prevention measures following opposition from influential Islamic leaders, who allege oral vaccination is unsafe and part of a secret U.S. plan to depopulate Africa.

The WHO polio eradication program is supported by the United Nations, the U.S. Center for Disease Control, the International Red Cross and Red Crescent, 16 donor countries and the European Union. All regard the vaccine as safe.

Atiku, speaking to country representatives of the UN Development Program and United Nation's children's agency UNICEF, said there was a need "for all stakeholders to meet and find a solution to the various issues surrounding the analysis of the polio vaccines".

UNICEF official Ezio Gianni Murzi said that while polio had nearly been eradicated globally, Nigeria had recorded an increase of 40 percent in cases so far in 2003 compared to 2002.

UNDP official Teggegnework Gettu urged the federal government to quickly intervene in the controversy. He said all northern states in Nigeria bar one were afflicted by the polio virus.