(GIN) – The pharmaceutical company Pfizer has been hit by charges that it carried out improper trials on Nigerian children for an anti-meningitis drug. The Nigerian government is demanding $7 billion in damages for the families of children who allegedly died or suffered side-effects after being given Trovan. The firm denies any wrongdoing, saying the trials were conducted according to Nigerian and international law.

Pfizer–the world’s largest pharmaceutical company–tested the experimental drug in meningitis-stricken children in Kano in 1996. Some children reportedly died, and campaigners say several others developed mental and physical deformities.

The government says the children were injected with the drug without approval from Nigerian regulatory agencies. A separate case in the city of Kano–in which the state is seeking 2.7 billion in compensation–has been running for more than two years. On June 4, judges postponed that trial by a month, to allow the firm to appear before the Kano court. Trovan has been approved for use by adults, but not children, in the United States.