Nigeria has filed charges against the pharmaceutical company Pfizer, accusing it of carrying out improper trials for an anti-meningitis drug in 1996.

Families were urged to take their sick children to Kano's infectious diseases hospital to receive treatment.

This is where Pfizer was testing a new antibiotic, Trovan, which was given to some of the sick children.

About 200 children died and more developed deformities.

The Nigerian government says these were caused by Trovan and says Pfizer did not get authorisation before giving out the drug. It wants $7bn in compensation.

Pfizer denied this, says the trials were carried out according to local and international law and that Trovan helped save lives during the meningitis outbreak.

Trovan has since been licensed for use by adults in the US but not Nigeria.