At least seven people were killed and dozens injured, mostly suffering burns, after a huge explosion at a fuel distribution site in Ghana's capital, local authorities said on Sunday.

The blast on Saturday evening was heard across much of the city, sending a giant fireball into the sky above the eastern part of Accra and causing frightened residents to flee their homes in large numbers. Others were forcibly evacuated.

At least seven people died and 132 were injured, a statement from the Ministry of Information read out on local radio said on Sunday. About half of them had already been treated and discharged, it said

The site includes a liquefied petroleum gas storage depot and two service stations run by state-owned GOIL and oil major Total. It was not immediately clear where or how the explosion began.

Witnesses said people had already began fleeing the area ahead of the blast because of the pungent odour of gas - a factor that likely reduced casualties.

Neither Total nor GOIL responded to requests for comment.

Ghana, a relatively new oil and gas producer, has suffered several recent accidents including an explosion in 2015 that killed around 100 people. Like many teeming African cities, Accra's infrastructure has failed to keep up with its population, which has shot up to 7 million.

At the scene of the fire on Sunday, scattered fruit and broken coconuts from street vendors were strewn near the wreckage next to burnt-out cars and a fuel lorry, a Reuters witness said.

Vice President Mahamudu Bawumia described the accident as "one too many" and promised to toughen safety measures.

Several onlookers there expressed anger that the government had not done more to prevent another fatal accident in the city.

"It's annoying to see all the big men in our society trooping to this place as if this is the first time we have such an incident," said Joshua Vokeh, a 38-year-old mini bus driver.

"They visit, talk tough and make promises, drive off and it ends there."