The resumption of polio vaccination in Nigeria's northern state of Kano has been thrown into doubt after the state government rejected conclusions of a federal panel of experts that the vaccine promoted by the United Nations is safe. But, governors in other northern states have endorsed the use of the vaccine.

The federal panel, made up of scientists, government officials and Islamic leaders, reported to President Olusegun Obasanjo that the U.N. vaccine is not contaminated with harmful substances.

But state and Islamic leaders in Kano insist their own tests show the vaccine supplied by the United Nations is contaminated with anti-fertility agents. A state official was reported as saying Kano will not resume vaccination until it procures the serum from its own sources.

The state, which is at the heart of the fastest growing outbreak of polio, has refused to participate in the vaccination program, sparking fear the crippling virus will spread to neighboring countries.

The presidential spokeswoman, Remi Oyo, says that northern governors attending a briefing Wednesday by the expert panel pledged their support for the U.N. vaccination campaign.

"What is important here is that the northern governors themselves who were present here today said that it is important for them to vaccinate the children against polio," she said. "Not only for the sake of the children and humanity and Nigerian future, but so that the whole world can be finally rid of the deadly and debilitating disease of polio."

The World Health Organization has warned that Kano's refusal to participate in the vaccination campaign puts at risk the success of its polio eradication program.