"To date, there are six states: Kano, Kaduna, Plateau, Bauchi, Katsina and Zamfara, and the Federal Capital Territory," of Abuja where bird flu has been confirmed," Information Minister Frank Nweke told reporters in Abuja.
"The situation is under control to the extent that the outbreak is mostly localised to contiguous states," he said, adding that there was "no report of any human infection in spite of the extensive diagnostic tests that are ongoing."
Mr Nweke said the government would shortly start paying compensation to farmers whose birds had been slaughtered, with the sums ranging from 250 naira (less than two dollars/1.5 euros) per chicken to 20,000 naira for every ostrich.
The government had also received stocks of "Tamiflu currently used in the management of the flu amongst humans in countries where this has occurred," Mr Nweke said.
Nigeria's health minister had asked for 250,000 doses of the anti-viral drug Tamiflu. Nigeria had earlier confirmed bird flu in three northern states.
The latest tally brings the number of states affected by avian influenza to six, excluding the federal capital Abuja and its surrounds which form the Federal Capital Territory.
UN health officials fear that the virus might get a hold on Africa's teeming cities, where many people's immune systems are compromised by AIDS and malnutrition.
Mass culling failing
The mass culling of birds suspected of having the H5N1 strain of bird flu is failing to check the global spread of the virus, according to the chief veterinary officer of the UN Food and Agriculture Organisation.
"Where we are failing is to eradicate the virus, because the virus exists in many reservoirs, including wild birds," Joseph Domenech told BBC World Service radio.
"So in that case, you can understand very easily that we have to live with and through better surveillance and reporting (to) face this situation and respond to any new outbreak."
Tests on nine dead swans in Britain have confirmed that they did not die from the H5N1 strain of bird flu, according to the UK’s Department of the Environment, Food and Agriculture (DEFRA).
"We have just spoken to the laboratory and they confirm that the tests were negative," a DEFRA spokeswoman told AFP in London, adding that it did not intend to give a "running commentary" on every bird tested.
The birds were found dead over the weekend, after the discovery that a wild duck in France had died from the highly pathogenic H5N1 strain raised fears that bird flu could soon reach Britain.
EU holds back help
Meanwhile the European Commission has told the EU's member states to use existing rules to help poultry producers hit by scares over bird flu, ruling out EU community support at this stage.
Agriculture ministers from the 25 member states meeting in Brussels joined the commission, the EU's executive arm, in calling for calm about the deadly H5N1 strain of the virus, so far found only in wild birds.
The virus has been found in six EU member states: Austria, France, Germany, Greece, Italy and Slovenia.
"There are different ways for member states to help poultry producers," said Agriculture Commissioner Mariann Fisher Boel.
Brussels was ready to authorise national aid in the form of technical measures that already existed, such as low-interest loans to producers, provided member states respected community rules, she said.
"We will see what can be done," she said. "If not, I shall be open to other solutions. I shall not close any door if the situation gets worse."
As the most deadly form of bird flu, the H5N1 virus strain, is found in western Europe on an almost daily basis, poultry sales have plunged by 70 percent in Italy, 40 to 50 percent in Greece and 15 percent in France.