By Imogen Foulkes
BBC correspondent in Geneva
The northern Nigerian state of Kano has confirmed it is to resume polio vaccination in early July, the World Health Organization says.
Polio has spread beyond Nigeria's borders
An immunisation campaign was suspended there last year following objections from religious leaders.
The announcement that Kano will start vaccinating again comes as a huge relief to the WHO in Geneva.
In the past year officials have watched the spread of polio from Nigeria with mounting concern and frustration.
Ten previously polio-free African countries have been reinfected.
The most recent case is the Sudanese province of Darfur, which is already suffering the effects of a 21-month old conflict. Now, polio has re-emerged there too.
Just last week the WHO announced an emergency vaccination campaign of 74 million children in 22 African countries in a effort to stop the virus spreading.
But there was still no word from Kano where Muslim religious leaders said they believed the vaccination, which they classed as Western, could be harmful.
Now the WHO says it has an assurance from the governor of Kano that the polio vaccine is safe and that the immunisation campaign will resume in early July.
The WHO hopes this will put its campaign to eradicate polio worldwide by 2005 back on track, but the renewed vaccination campaign still comes too late for the 257 Nigerian children who have been paralysed by polio since the start of this year.