A gas tanker truck ignited an inferno at a crowded industrial gas plant in Nigeria on Thursday, killing more than 100 people who were lining up to refill their cooking gas cylinders in time for Christmas.

The disaster took place in Nnewi, a predominantly Christian city in southeast Nigeria. By the time firefighters managed to put out the blaze, there were charred remains of more than 100 bodies.

A witness, Emeka Peters, said the fire broke out at about 11 am when a tanker truck that had finished discharging fresh gas at the Chikason Group Gas plant left without waiting the prescribed cooling time.

"The fire exploded like a bomb, and the whole gas station went up in thick, black smoke amid an explosion from cooking gas cylinders," Peters said.

"Many people were killed, and most of them were those who had been in the station ... all day to get their cylinders refilled."

He said the fire raged for hours.

Peters, 36, said the few badly injured victims were evacuated to Nnamdi Azikiwe University Teaching Hospital in Nnewi.

"Many of them were burned beyond recognition, and I doubt if many family members of the dead victims would be able to identify the remains of their loved ones," said Peters.