According to a Reuters report, Nigeria's federal government and its Kano state government are suing the US drug giant for $8.5bn (€6bn).
On Wednesday, Pfizer will also have to face civil and criminal charges brought by both governments.
Nigeria alleges that Pfizer deceived patients and caused the death of 11 children in 1996 after it conducted a clinical trial of Trovan in the country.
The drug was, at the time, a late-stage experimental antibiotic treatment for meningococcal meningitis.
1996 marked the beginning of a major meningitis epidemic in Nigeria which killed almost 12,000 children over a six-month period and Pfizer claims, in a statement of defence, it set up the Trovan study at the Infection Disease Hospital (IDH) in Kano, in northern Nigeria, with the objective of bringing to that country "a life saving, innovative, less painful and cost-effective form of antibiotic to treat epidemic meningococcal meningitis."
"There was a compelling reason to look at Trovan because it was an oral formulation, it was known to have shown efficacy in meningitis and was a five-day treatment so it was perfect for an epidemic setting," Ngozi Edozien, managing director of Pfizer in West Africa, told Reuters yesterday.
According to Pfizer, the clinical study involved 200 children in Kano, after the area suffered the meningitis outbreak, and half of the patients received Trovan while the other half received a dose of an already approved meningitis treatment, Roche 's Rochephin (ceftriaxone) .
Prior to this, Trovan had already been tested in 5,000 patients elsewhere, said Pfizer.
However, according to an article in the Washington Post in May, the drug had never before been tested in children with meningitis and Nigerian officials are claiming in the lawsuit that Pfizer's actions resulted in "the deaths of 11 children and left others deaf, paralysed, blind or brain-damaged".
Currently, the drug is not marketed in Europe and is only available in the US for adults, although its use is restricted due to its reported association with liver toxicity and deaths.
The Nigerian government also alleges that Pfizer failed to obtain all the required approvals for the trial and did not get proper consent from the patients' families.
Pfizer denies every material allegation and believes that "the Kano State civil lawsuit has no merit and is both frivolous and a gross abuse of the legal process 11 years after the fact," the firm said in a statement released in July.
In its statement, the firm said it did not misrepresent or conceal any facts in its decision to come to Nigeria, adding its intention "was clear from the beginning".
Furthermore, Pfizer said that before conducting the Trovan clinical study in Kano, it "sought and obtained all necessary approvals from relevant federal and state government agencies in Nigeria," and has more than 12 letters between the company and the US and Nigerian regulators discussing and approving the study.
The scandal around the Trovan trial resurfaced when in 2001, the Nigerian Ministry of Health appointed a panel of experts to look into the 1996 trial.
However, according to Pfizer, the resulting report was never made public until an article in the Washington Post reported excerpts from it last year.
The health committee report concluded that Pfizer's actions violated Nigerian law, the international Declaration of Helsinki and the UN Convention on the Rights of the Child.
Nigeria subsequently brought a previous lawsuit against Pfizer in a US court although this was dismissed in 2005 by a federal judge who said the case should instead be heard by a Nigerian court, which this latest lawsuit will be.
In addition, in July Pfizer also filed a lawsuit in federal court in Abuja, Nigeria, charging that the report, in which the Nigerian government has based many of its claims against the company is "illegal, inaccurate and should be quashed."
Pfizer was not available for comment at the time of publishing.