Authorities, battling to stem an escalating insurgency, covered up a bomb attack in the financial capital Lagos by claiming a blast near a major fuel depot was an industrial accident, according to an AFP investigation.
The explosion ripped through an area of Lagos on 25 June, just hours after a suspected Boko Haram car bombing in the administrative capital Abuja, which killed 21 people and stoked fresh fears that the group's deadly campaign was spreading.
The Lagos blast in the Apapa district, on a main road feeding Nigeria's busiest port and in an area housing most of the city's fuel depots, was blamed on a cooking gas cylinder which exploded, with no casualties.
But AFP has seen photographs of the scene showing a destroyed car plus damage to surrounding vehicles, which the British Army's former head of bomb disposal said left no doubt as to the cause.
"This was definitely an incident involving the use of high explosives," Bob Seddon, an Iraq and Afghanistan veteran and a specialist in improvised explosive devices (IEDs), told AFP in an email exchange after reviewing the images.
"The type of blast effects and fragmentation pattern you would get from a gas explosion are quite different," the former Royal Logistics Corps colonel said, assessing that 25-50kg of improvised high explosive were used.
Senior foreign diplomats also indicated privately that the blast was deliberate, attributing the official denials to fears over the potential effects of a confirmed first attack on Lagos, which drives the country's economy.