A US-backed Kurdish-led force said a prison overrun by the terrorist group calling itself Islamic State (IS) in northeastern Syria is now fully under its control, thwarting a plot by the extremists to launch further, multiple attacks across the volatile region.

It also appealed for the international community’s help in taking responsibility for the tens of thousands of IS fighters and their families in detention centres and camps under its control.

The Syrian Democratic Forces (SDF) said more than 120 of its fighters and prison workers died in the 10-day stand-off at the Gweiran prison, also known as al-Sinaa prison, which houses at least 3,000 IS detainees.

Some 374 IS militants, including the initial attackers, were also killed, it added.

The January 20 assault on one of the largest detention facilities in Syria has turned the city of Hassakeh into a conflict zone and forced thousands of residents to flee.

The fighting drew in the US-led coalition, which carried out air strikes and deployed American personnel in Bradley Fighting Vehicles to the scene.

It was the biggest military operation by the extremist group since the fall of its self-declared caliphate in 2019 and came as the militants staged deadly attacks in both Syria and Iraq that stoked fears that IS may be staging a comeback.

At a press conference on Monday, SDF commander Nowruz Ahmad said the IS prison attack was aimed at liberating a number of terrorist detainees, but also formed part of a broader plot that IS had been preparing for a long time.

According to seized documents and confessions of some of the attackers, the extremist group had planned attacks on other neighbourhoods in Hassakeh, the town of Shaddada and areas of Deir el-Zour in eastern Syria.

Also planned were simultaneous attacks on the al-Hol camp, which houses thousands of families of IS members.

“They wanted to launch a massive attack on the region, and once again to spread their terror and impose darkness on the people of the region and revive the terrorist organisation once again,” Ms Ahmad said.

She also accused neighbouring Turkey, an archenemy of the Kurds, of facilitating and assisting in the organisation of the prison attack but did not provide evidence.

Ms Ahmad said the attack demonstrated the need for radical solutions to the ongoing presence of tens of thousands of IS detainees and their families in northeastern Syria, as well as expediting the trial and prosecution of IS terrorists.

In Washington, State Department spokesman Ned Price commended the SDF for its effective response to the prison attack.

IS’s “desperate and violent tactics are a grave reminder to the world that the terrorist group remains a threat that can and must be defeated”, he said in a statement.

“Due to the effective response of the SDF, in partnership with US and coalition forces, senior Isis leaders were captured or killed during the attempt to free detained Isis members from detention.”