Libyan authorities have opened an investigation into the collapse of two dams that caused a devastating flood in a coastal city as rescue teams searched for bodies on Saturday, nearly a week after the deluge killed more than 11,000 people.

Heavy rains caused by Mediterranean storm Daniel caused deadly flooding across eastern Libya last weekend.

The floods overwhelmed two dams, sending a wall of water several metres high through the centre of Derna, destroying entire neighbourhoods and sweeping people out to sea.

More than 10,000 are missing, according to the Libyan Red Crescent. Six days on, searchers are still digging through mud and hollowed-out buildings, looking for bodies and possible survivors. The Red Crescent has confirmed 11,300 deaths so far.

Claire Nicolet, who heads the emergencies department of the Doctors Without Borders aid group, said rescuers found “a lot of bodies” on Friday and were still searching.

“It was a big number ... the sea is still ejecting lots of dead bodies, unfortunately,” she told The Associated Press.

She said massive aid efforts were still needed, including urgent psychological support for those who lost their families. She said the burial of bodies is still a significant challenge, despite some progress in search and rescue efforts.