AFP/ Lagos

A huge Christmas Eve explosion at an industrial gas plant in southeastern Nigeria left several people charred beyond recognition, police said Friday, as fatality numbers ranged from single digit figures to scores. 

The blast at the Inter Corp Oil Limited gas plant, a subsidiary of Nigerian conglomerate Chicason Group, started around noon on Thursday, engulfing the industrial city of Nnewi in black clouds of billowing smoke.

The fire raged on for hours gutting surrounding buildings and cars.

By the time firefighters doused the last flames, there were charred corpses on the ash-covered ground, according to local reports.

Gruesome mobile phone photos taken at the scene  showed blackened bodies lying face down in smouldering rubble. 

"It was a huge inferno," police spokesman Ali Okechukwu told AFP.

"We have found six bodies outside the perimeter, two more bodies were found in the adjoining building, bringing the total number of casualties to eight," Okechukwu said.

"Six more persons were injured and referred to the hospital."

Okechukwu, who was en route to the blast scene, said an investigation into the explosion was under way.

The gas-fuelled fire spread to a large surrounding area instantly, National Emergency Management Agency (NEMA) spokesman James Eze told AFP.

- 'Everything was burnt' -

"About 300 metres from the gas line all the plants there were burnt, houses from 400 metres away were affected, heavy machines too," Eze said, speaking by phone from the Nnamdi Azikiwe University Teaching Hospital where victims of the blast were taken for treatment.

Eze put the total number of casualties at four, barring any missing people who were burnt without any trace.

"The fire (was) so strong as to burn the bones into ashes, but nobody has come forward with a missing person," Eze said.

There are conflicting accounts about the cause of the explosion and the authorities have not explained what triggered it.

Some local reports say that the blast occurred  after a truck was off-loading butane cooking gas for customers stocking up on fuel for Christmas festivities.

Others say it was triggered when a leaking consignment of gas was being moved to the company dump.

"The cause is yet to be determined. A few people lost their lives. Some people suffered burns of various degrees," said Anambra state governor, Willy Obiano, who visited the scene of the accident.

A mainly Christian city, Nnewi is known as a busy hub for trading spare vehicle parts.

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

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

In July, 12 people died and three were injured after an explosion while doing repair work on a pipeline in the Niger delta.

Over the past decade, hundreds of people in the continent's biggest economy have been killed in explosions.

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