Nasiru Sani Gwarzo told journalists that samples taken from bodies that were yet to be buried turned positive.

He said initial mapping showed that the virus may have spread as people visited the sick and attended burials.

"It is necessary for people of Kano to wake up from their slumber... this is a serious issue," he was quoted as saying by local media.

The mysterious deaths were first mentioned by grave diggers who noticed an increase in burials at the cemetery. The Kano state government initially linked the deaths to underlying medical conditions.

The country has 2,558 confirmed cases of the virus, with Kano the second leading in the number of cases after the commercial city of Lagos.