"We have eight killed by the explosion at the Rajma military base as well as more than 20 injured," Imad Talahma, a neurosurgeon at Benghazi's medical city.

Sources at the city's other two main hospitals had earlier given a combined toll of 19 dead from the twin blasts at the munitions depot just outside Benghazi, the main rebel held city in eastern Libya, on Friday.

"We're not quite sure whether it was sabotage, an accident or an air strike, but nobody saw any planes," Mustafa Gheriani, a spokesman for the rebels' self declared national council in Benghazi, said.

"We don't expect to find people intact (on the site). It has been estimated that around 40 people were in the compound. The explosion destroyed a large area and affected the residential area," he added.