The flash flood, which witnesses likened to a tsunami, broke through two ageing dams on September 10 after a hurricane-strength storm lashed the area around Derna, a port city in Libya's east.
The officials are suspected of "bad management" and negligence, a statement from the prosecutor general's office said, adding that they served currently or previously in offices responsible for water resources and dam management.
On Saturday the official death toll passed 3,800, and international aid groups have said 10,000 or more people may be missing.
After opening a probe, Libya's prosecutor general Al-Seddik al-Sur said more than a week ago that the two dams upstream from Derna dad been cracked since 1998.
But repairs begun by a Turkish company in 2010 were suspended after a few months when Libya's 2011 revolution flared, and the work never resumed, the prosecutor said on September 16, vowing to deal firmly with those responsible.
The 2011 NATO-backed revolt toppled longtime dictator Moamer Kadhafi, leading to more than a decade of start-stop conflict.
Libya is now divided between an internationally-recognised Tripoli-based administration in the west -- to which Sur belongs -- and another in the flood-struck east.
Eastern forces years ago launched a failed assault on the capital which ended in a 2020 ceasefire.
Since then a period of relative stability has held and allowed war-ravaged Libya to try to rebuild.
- Wall of water -
The first dam to collapse in the disaster was the Abu Mansur dam, 13 kilometres (eight miles) from Derna, whose reservoir held 22.5 million cubic metres (nearly 800 million cubic feet) of water.
The deluge then broke Al Bilad, the second dam, which had a capacity of 1.5 million cubic metres and is just a kilometre from the coastal city.
The wall of water and debris swept through the normally dry riverbed or wadi that cuts through the city centre.
Both dams were constructed by a Yugoslav company in the 1970s, "not to collect water but to protect Derna from floods,",Sour said earlier.
Since Libya's 2011 revolution, a budget has been allocated every year to repair the two dams, but none of the successive governments has undertaken the work, according to an official.
In a 2021 report from the Libyan audit bureau, officials criticised "procrastination" on resuming repair work at the two dams.
In November 2022, engineer and academic Abdel Wanis Ashour warned in a study that a "catastrophe" threatened Derna if the authorities did not carry out maintenance on the dams.
Forum