Suspected avian influenza was recorded in northern Nigeria´s Sokoto State, a day after the disease reportedly infected 5,000 birds in nearby Kastina state, a senior official said.

Forestry and Animal Health Commissioner Abdulkadir Junaidu said a disease suspected to be bird flu had killed at least 7,000 chickens on a farm in Kebe district 10 kilometres (six miles) outside the state capital.

"The rate at which the birds are dying is unusual and alarming, which is why we are worried that it could be bird flu outbreak", Junaidu said.

"So far 7,000 chickens have died on the affected farm and we have started depopulating the remaining 16,000 chickens on the farm and all other birds on backyard poultry plots in the surrounding villages", he added.

Junaidu said movement of chickens in and out of the affected area has been banned to avoid further spread while samples of the infected chickens had been taken for laboratory test.

The suspected outbreak came barely 24 hours after a similar case was reported in nearby Kastina state on Friday.

The deadly H5N1 strain of avian influenza was first detected on a farm in Jaji, outside the northern city of Kaduna, in February 2006, from where it spread to other parts of the country and the region.

More than 450,000 chickens have already been slaughtered in Nigeria, mainly in the north, but no human case has so far been reported.