Nigeria on Thursday confirmed that the H5N1 strain of bird flu has spread from seven to 11 states within a week, resulting in the deaths of tens of thousands of poultry but no human cases.

Agriculture Minister Akinwumi Adesina told an emergency meeting on the outbreak that "as of yesterday (Wednesday) a total of 11 states, have reported positive cases".

Cases have been recorded in Kano, Plateau, Gombe and Jigawa in the north, Lagos, Ogun and Oyo in the southwest. Imo in the southeast is also affected, with Rivers, Delta and Edo in the south.

The minister said that as of Wednesday, 232,385 birds were exposed to the virus and 51,444 had died -- up from nearly 140,000 exposures and just over 22,000 deaths on January 21.

"We are not in a state of any epidemic, we are closely monitoring the situation and taking aggressive containment measures," said Adesina.

"There is no cause for alarm but we must now move with greater speed and decisiveness."

Kano, Nigeria's largest state in the north, has been worst hit by the outbreak with 136,905 infected birds and 17,987 deaths; Lagos had 38,845 cases and 4,732 deaths.

Adesina said last week that the first cases were confirmed on a commercial farm in Kano city and at a live bird market in Lagos State on January 8.

The government has approved 145 million naira ($767,400, 676,000 euros) to compensate farmers by the outbreak.

The H5N1 strain of the bird flu virus has killed more than 400 people worldwide since it first appeared in 2003, most of them in southeast Asia.