Large explosion rocks Nigerian city Lagos

Emergency services are battling fires and relief workers are searching for survivors after a large explosion in the Nigerian city of Lagos.

Both the cause and the possible death toll from the explosion, which rocked areas in the city's southwest on Sunday morning, remain unclear.

Authorities said the initial blast devastated a large number of buildings in three districts - Ado Soba, Abule Ado and Amuwo Odofin - and that more structures continued to burn.

"The initial explosion destroyed more than 50 buildings and the resulting fire has already spread to pipelines," National Emergency Management Agency spokesman Ibrahim Fariloye said.

Photos from the scene showed plumes of black smoke rising into the sky from an expanse of wreckage.

A number of buildings were ablaze, while others had already collapsed.

Abule Ado in southwestern Lagos lies in the path of several oil pipelines which have been hit by explosions in the past, though officials indicated this was not the cause of Sunday's blast.

Sunday's blast occurred not far from a naval base.

Nigeria is one of Africa's biggest oil producers and the country's commercial capital Lagos is home to 21 million people.