Khalifa Hifter, who oversees a military dictatorship that rules the eastern half of the divided, oil-rich nation, is dominating the response to the disaster and could use it to further entrench his power.
The cries of protesters were part of a rising chorus of calls for answers from leaders across a divided Libya, specifically for an international investigation.
An aid worker said hundreds of bodies at a time were being placed in mass graves. Thousands died in the floods that hit the northeast of the country last weekend.
Libya s Tobruk-based Parliament voted on 16 May to dismiss Fathi Bashagha, as prime minister of parallel government in the east of the country and replaced him with his Finance Minister, Osama Hamad.