The deadly H5N1 bird flu virus was confirmed in two more Nigerian states on Thursday as authorities grappled to contain the disease with quarantine orders and culling.

Nigeria reported Africa's first confirmed cases on Wednesday of the highly pathogenic strain of avian influenza, which has forced the slaughter of more than 100 million birds in Asia and jumped to humans in Asia, Europe and the Middle East.

Farmers in northern Nigeria are rushing to sell dead chickens at cut-price rates before government bans are put into place.