Jul 25, 2007
Abuja accuses Pfizer of misleading patients during a 1996 trial of an anti-meningitis drug in Kano which killed and disabled dozens of children.
The government is seeking $7bn (£3.4bn) in damages from the US group. The state of Kano has also filed a criminal case seeking $2bn in damages.
Pfizer has denied all wrongdoing, saying the drug had been approved.
Among the most recent charges filed by Nigeria's government is the claim that the drug firm imported the drug illegally without the requisite trial certificate, but instead produced a false version.
While the criminal case was initially filed in May, it was not made public due to an absence of defendants.
Nigeria's legal system stipulates that defendants - which in this case include Pfizer, its Nigerian outlet as well as Nigerian executives and staff members - must be present for a case to go forward.
While the US Drug and Food Administration gave the go-ahead in 1997 for adult use of Trovan - the antibiotic drug in question - it did not do the same for children.
Nigeria says its regulatory authorities had not approved the then-unregistered drug, which was tested in Nigeria's north-western Kano State at the height of a meningitis outbreak.