A Nigerian court allowed the federal government on Wednesday to serve a summons on US-based drug maker Pfizer Inc to defend itself against a $6,5-billion lawsuit over a drug trial.

The federal government and the northern Nigerian state of Kano are suing Pfizer for a combined $8,5- billion in damages over the 1996 trial of Trovan, a new drug tested on children during a meningitis epidemic.

Pfizer says Trovan saved lives and the alleged victims were affected by meningitis, not Trovan.

More than 12 000 Nigerian children died in six months from the 1996 epidemic of meningitis, an infection of the nervous system that can kill in hours.

"Leave is hereby granted for the prosecution to serve ... the defendants," said Babs Kuewumi of the Federal High Court in the Nigerian capital, listing Pfizer Inc and four other defendants.

He adjourned the case to Oct 22.

Trovan had been tested on 5,000 people before it was used in Nigeria. It was licensed by the U.S. Food and Drug Administration for use on adults a few months after the Kano trial.

It briefly became one of Pfizer's top-selling drugs, with 300 000 prescriptions a month. But authorities imposed severe restrictions on its use three years later when it was found to cause serious liver injuries in some patients.

The federal lawsuit was first filed in the United States, but was thrown out in 2005 by a judge who said it should be heard in Nigeria.

The Kano state government's $2-billion civil suit against Pfizer also came up on Wednesday, but was adjourned until December 5 to allow both sides more time to study the case.

A criminal case based on the Trovan trials and brought by Kano state was also heard and adjourned to November 6 to enable the defendant to be served a court summons.

The attorney general of Kano state, Aliyu Umar, said he would be leading a delegation to hold talks with Pfizer on November 17 in the United States with a view to a possible out-of-court settlement.