Foreign Islamic State fighters held in overcrowded prisons and lawless refugee camps in north-east Syria – including about 60 Britons – should be put on trial there as part of an international effort to de-radicalise the region, according to senior local officials.

Politicians and soldiers from the Kurdish-led region said they needed western help to deal with the prisoners locally, including setting up a recognised war crimes tribunal, amid warnings that IS could otherwise rebuild.

Images emerged this week of the insanitary conditions in makeshift prisons where people of more than 50 nationalities were held in packed cells, sometimes 20 to a room. Meanwhile, local politicians admitted they had lost control of the refugee camps to IS radicals.

Dr Abdulkarim Omar, the de facto foreign secretary of the self-styled Autonomous Administration of North and East Syria, and the co-chair of its foreign affairs committee, said: “We call for the establishment of an international tribunal to prosecute those fighters here in our region.

“Those people, the IS criminals, committed their crimes in our region and against our communities. Evidence, proof and witnesses against them are in this region, and we can prosecute them.”

Omar, speaking before pictures of the prison interiors were published in the Times, admitted his administration was struggling with the postwar legacy. Omar said the region only received “5% of the resources it needs” from the international community to help. Officials repeatedly described the prisons and camps as a “ticking time bomb”.

Estimates of the number of IS fighters in detention vary. The administration puts the figure at 6,000, including 1,000 foreigners, but others say the true number is double that. Some have been in custody for two or more years without trial after IS sustained a series of battlefield defeats.

Refugee camps hold in excess of 100,000 people, mostly women and children, with the largest, the al-Hawl camp, holding more than 70,000.