DERNA, Libya -- Libya's flood disaster, which killed thousands in the city of Derna, also displaced more than 43,000 people, the International Organization for Migration said Thursday.

A tsunami-sized flash flood broke through two ageing dams upstream from the coastal city after the Mediterranean Storm Daniel lashed the area on September 10.

It razed entire neighbourhoods, sweeping untold thousands of people into the sea.

The official death toll stands at more than 3,300 -- but the eventual count is expected to be far higher, with international aid groups giving estimates of up to 10,000 people missing.

"An estimated 43,059 individuals have been displaced by the floods in northeastern Libya," the IOM said, adding that a "lack of water supply is reportedly driving many displaced out of Derna" to other areas.

"Urgent needs include food, drinking water and mental health and psychosocial support," it said.

Mobile and internet services were meanwhile restored after a two-day disruption, following protests Monday that saw angry residents blame the authorities for the high death toll.

Authorities had blamed the communications outage on "a rupture in the optical fibre" link to Derna, but some internet users and analysts charged there had been a deliberate "blackout".

Tripoli-based Prime Minister Abdelhamid Dbeibah announced that communications had been restored in the east, in a post on X, formerly Twitter, on Thursday.

War-scarred Libya remains split between Dbeibah's UN-backed and nominally interim government in the west, and another in the disaster-hit east backed by military strongman Khalifa Haftar.

- 'Arrests of critics' -

The eastern authorities "must immediately lift all undue restrictions... and facilitate the delivery of humanitarian aid to all affected communities", Amnesty International said in a statement on Thursday.

The rights group, citing witnesses, reported "arrests of critics and protesters" in Derna, decrying "efforts to choreograph and control media access" to the disaster-hit city.

The dams that burst had developed cracks as far back as the 1990s, Libya's top prosecutor has said, as residents accused authorities of negligence.

Much of Libya's infrastructure has fallen into disrepair in the chaos since a NATO-backed uprising toppled and killed dictator Moamer Kadhafi in 2011.

Haftar's forces seized Derna in 2018, then a stronghold of radical Islamists, and with the reputation as a protest stronghold since Kadhafi's days.

The US embassy in Libya said the ambassador Richard Norland and the commander of the US military's Africa Command, Michael Langley, flew into the main eastern city of Benghazi on Thursday with 13 tonnes of aid.

The "critical supplies" in the shipment fincluded blankets, hygiene products and emergency shelters, the embassy posted on X.

Africom chief Langley and Norland also met with Haftar "to discuss the importance of forming a democratically elected national government, reunifying the Libyan military, and safeguarding Libyan sovereignty by removing foreign mercenaries", the embassy said.

- Suspects 'identified' -

The Tripoli-based government said security forces had located bodies between Derna and Al-Baida, to its west, with emergency responders dispatched to the area to recover them.

A team from the Abu Dhabi police force specialising in identifying disaster victims arrived in eastern Libya to assist operations.

The mission includes experts in forensic medicine, and DNA and fingerprint identification, team leader Issa Ahmad al-Awadhi told reporters.

In a televised interview on Wednesday evening, Libya's prosecutor general Al-Seddik al-Sour promised "rapid results" in the investigation into the cause of the tragedy.

He added that those suspected of corruption or negligence "have already been identified", without naming them.

Amnesty's Middle East and North Africa deputy director, Diana Eltahawy, said there was "an urgent need to establish the facts and circumstances surrounding the staggering loss of life and destruction".

"This includes examining whether Libyan authorities and those in de facto control of affected areas failed to protect the population's rights to life, health and other human rights," Eltahawy said.