Communications went down, some journalists were pushed out and a U.N. aid team was blocked from the flood-hit city of Derna on Tuesday, as the authorities sought to contain public anger over the failure to prevent Libya's worst ever natural disaster.

A week after a flood wiped out much of the centre of the city, furious Derna residents demonstrated on the streets and torched the home of the mayor overnight. They accuse the authorities of failing to maintain the dams that protected the city, and failing to evacuate residents before the storm.

By Tuesday morning, the situation was again calm, but internet and phone links were down. The regional administration said it had suspended the mayor and fired the entire city council.

The United Nations Office for the Coordination of Humanitarian Affairs (OCHA) said search and rescue teams, emergency workers and U.N. staff already inside Derna were still operating, but a team due to head there from Benghazi had been halted.

Some journalists for media, including Arabic-language channels that have been broadcasting from the city for days, reported on Tuesday that they had been ordered out.

The overnight protests, the first sign of unrest on the ground since the flood, showed the degree to which the disaster poses a challenge to the authorities in Libya's east, now under control of regional strongman Khalifa Haftar.

"Haftar's forces are under pressure to show they have control of the situation, and that they can handle the fallout. All eyes will be on them to see if they go for repression," said Tim Eaton of Britain's Chatham House think tank, who added that harsh measures would be a "miscalculation".

"This will remain a seed of anger and contention for a long time to come."

Officials offered benign explanations for the communications cut-off and the apparent orders to some journalists to move out of the Mediterranean coastal city of 120,000 people. There was no immediate explanation for blocking the U.N. mission.

A spokesperson for the state-owned Libyan Telecommunications Holding Company, Mohamed Albdairi, told Libya Alahrar television that the communications had gone down in the area because some fiber optic cables had been severed. Engineers were investigating whether this was due to excavation work or sabotage, and looking to repair it, he said.

Hichem Abu Chkiouat, minister of civil aviation in the administration that runs eastern Libya, told Reuters by phone that some reporters had been told to stay away from rescue operations, but denied this was linked to security or politics.

"It is an attempt to create better conditions for the rescue teams to carry out the work more smoothly and effectively," he said. "The large number of journalists has become an impediment to the work of rescue teams."

Officials have given widely varying death tolls since dams above Derna burst in a storm on Sept. 10, unleashing a torrent that swept away the heart of the city. The World Health Organization has confirmed 3,922 deaths. Thousands more are missing, with countless bodies washed into the sea.

VICTIMS MANY TIMES OVER

In New York, U.N. Secretary-General Antonio Guterres told the General Assembly that Derna's residents were "victims many times over", of war, climate change and "leaders – near and far – who failed to find a way to peace".

"The people of Derna lived and died in the epicentre of that indifference - as the skies unleashed 100 times the monthly rainfall in 24 hours ..., as dams broke after years of war and neglect ..., as everything they knew was wiped off the map," he said.

"Even now, as we speak, bodies are washing ashore from the same Mediterranean Sea where billionaires sunbathe on their superyachts."

On Monday evening, demonstrators crowded into the square in front of Derna's landmark gold-domed Sahaba mosque chanting slogans. Some waved flags from atop the mosque's roof. Later in the evening, they torched the house of Mayor Abdulmenam al-Ghaithi, his office manager told Reuters.

A week after the disaster, swathes of Derna remain a muddy ruin, roamed by stray dogs, with families still searching for missing bodies in the rubble.

Angry residents say the disaster could have been prevented. Officials acknowledge that a contract to repair the dams after 2007 was never completed, blaming insecurity in the area.

Libya has been a failed state for more than a decade, with no government exercising nationwide authority since Muammar Gaddafi was toppled in 2011. Derna has been controlled since 2019 by the Libyan National Army which holds sway in the east. For several years before that it was in the hands of militant groups, including local branches of Islamic State and al Qaeda.

Mansour, a student taking part in Monday's protest, said he wanted an urgent investigation into the collapse of the dams, which "made us lose thousands of our beloved people".