Military operations against the "Islamic State of Iraq and Syria" (ISIS) in Syria are wrapping up, and the last pockets of the group's fighters will be flushed out within a month, a top commander said.

"The operation of our forces against ISIS in its last pocket has reached its end and ISIS fighters are now surrounded in one area," said Mazloum Kobani, who heads the Syrian Democratic Forces (SDF).

With backing from the international coalition, the SDF are in the last phase of an operation to defeat the group in its Euphrates Valley holdouts in eastern Syria.

"We need a month to eliminate ISIS remnants still in the area," Kobani said Thursday from near the north-eastern Syrian city of al-Hasakeh.

Intense fighting in the area known as "the Hajin pocket" has left hundreds dead on both sides, according to the Syrian Observatory for Human Rights.

'Sleeper cells'

ISIS lost the town of Hajin late last year and the subsequent collapse of its defences saw the Arab-Kurd alliance conquer one village after another.

Kobani said the battle had been complicated as ISIS shifted its strategy after the SDF ousted the group from its de-facto Syrian capital of al-Raqa in 2017.

New tactics include "sleeper cells everywhere, secretly recruiting people again, and carrying out suicide operations, bombings, and assassinations", he said.

"We expect there will be an increase in the intensity of ISIS operations against our forces after the end of their military presence," he said.

ISIS has retained a presence in Syria's vast Badiya desert and has claimed a series of attacks in SDF-held territory.

The SDF have been the main ground partner in Syria of the international coalition, and have recently turned to the Syrian regime to guarantee their survival, though Kobani said negotiations were proving difficult.

'Special status'

"Any political agreement should include the special status" of the SDF after they fought ISIS "on behalf of all humanity and even the Syrian army", Kobani said.

"This is our red line and we will not concede this."

The SDF "protected north-eastern Syria... liberated these areas, and have the right to continue protecting the region", he added.

The SDF could "agree to be part of the national army of a future Syria, but only on the condition they keep their special status", Kobani said.

Damascus has rejected self-rule in north-eastern Syria, but Kurdish leaders started talks in July in a bid to seek some form of decentralisation.

"The discussions are ongoing but have not yet reached any positive result," Kobani said. The regime "keeps on thinking it can go back to the way it was before 2011. It still hopes it can take military control of the whole region".

"It needs... to understand that is impossible."