Hundreds of ISIS members in Syria released by Kurdish authorities

The 631 prisoners were freed as part of an amnesty requested by tribal leaders

The families of ISIS fighters are among around 70,000 people crammed into the Kurdish-run Al Hol camp in north-east Syria. AFP

Kurdish-led authorities released hundreds of ISIS militants imprisoned in northern Syria on Thursday, as part of a general amnesty in the region controlled by the US-backed fighters.

Amina Omar, head of the Syrian National Council, said the 631 released ISIS members had “no blood on their hands" and  repented having joined the terrorist group.

“They are people who can be reformed,” Omar said shortly before the men were released.

The Syrian Democratic Council said another 253 prisoners will have their terms cut in half.

It said the amnesty and the release followed requests by tribal leaders in north-eastern and eastern Syria.

Kurdish authorities operate more than two dozen detention centres across north-eastern Syria, holding about 10,000 ISIS fighters.

Among them are about 2,000 foreigners whose home countries have refused to repatriate them, including about 800 Europeans.

ISIS, which at the height of its power in 2014 controlled a third of both Iraq and Syria, lost its last sliver of land last year when the US-backed Syrian Democratic Forces captured the eastern Syrian village of Baghouz.

Since then the extremists have gone underground, carrying out hit-and-run attacks, mostly against Syrian government forces and the Kurdish-led fighters.

This month, the regional authority said it would allow Syrian citizens to leave a sprawling camp that houses tens of thousands of women and children, many of them linked to ISIS.

Most of the detainees at Al Hol camp are Syrian and Iraqi women and children.

Another highly secured settlement within the camp is known as the Annex and is home to some 10,000 hard-line ISIS supporters from other countries.

The overpopulated camp is home to 65,000 people and has been a burden to the Syrian Democratic Forces and the Kurdish police in charge of security there.

Crime rates have been high inside the camp and some of the women have tried to escape.

Over the past 10 days dozens of families have left the camp.