LAGOS (AFP, REUTERS) - As many as 100 people were killed by an explosion at a gas plant in southeastern Nigeria, a local journalist at the scene said on Friday (Dec 25).

"I saw around 100 charred corpses," David Onwuchekwa said. An official at the state relief agency NEMA did not confirm the toll, saying the agency's workers were still assessing the site.

The blast happened on Thursday (Dec 24) when a truck was discharging butane gas at the facility in Nnewi town in Anambra state while customers were refilling their gas bottles, residents said.

The blast at the Inter Corp Oil Limited gas plant, a subsidiary of Nigerian conglomerate Chicason Group, started at 1pm on Thursday, swallowing the plant in a fire that gutted surrounding buildings and vehicles in Nnewi city.

"Definitely more than two people are dead," police spokesman Ali Okechukwu told AFP earlier on Friday. "It was a huge inferno."

Okechukwu could not confirm local reports that more than 50 people were killed, saying an investigation was underway. "A few persons are feared dead after the explosion," Okechukwu said over the phone from Awka, the capital of Anambra State.

"As of yesterday evening, the underground tunnel tank was still burning, but it had been stopped from spreading to other facilities."

Nigeria is Africa's largest oil producer, deriving the bulk of its money through the commodity.

Accidents happen frequently in the country, where pipelines are often damaged by people stealing crude oil.

The country loses an estimated 300,000 barrels a day to gangs that syphon crude from pipelines in the oil-rich southern states, according to the state-owned Nigerian National Petroleum Corporation.