At least 80 people were killed in an explosion at an illegal oil refinery in southern Nigeria, according to emergency services on Sunday, while local media confirm that the death toll has exceeded 100.

The explosion occurred late Friday at an illegal site between the oil-rich southern states of Rivers and Imo, according to the police.

Eviany Nagi from the National Emergency Agency at the scene told AFP, "We found at least 80 bodies with severe burn marks at the site," adding that the number may rise further.

He stated, "We learned of many bodies in the nearby bushes and forests due to the attempt of some illegal operators (of the refinery) and those responsible for them to escape to a safe place."

Nagi explained that several burnt cars and containers used to collect stolen crude and petroleum products were scattered at the site.

Local media reported that more than one hundred people were killed in the explosion.

Illegal crude refining is a common practice in oil-rich southern Nigeria, where thieves sabotage oil pipelines to steal crude which they refine and sell on the black market.

Most people in the Niger Delta suffer from poverty despite their country being the largest oil producer on the continent, producing about two million barrels daily.