OMAR OIL FIELD, Syria — Syrian fighters backed up by artillery fire from a US-led coalition pressed their assault Monday to retake a last morsel of territory from Daesh (the so-called IS) group, a war monitor said.

More than four years after the extremists declared a “caliphate” across large parts of Syria and neighboring Iraq, several offensives have whittled that proto-state down to a tiny holdout.

The Kurdish-led Syrian Democratic Forces (SDF) on Saturday announced the final push to expel hundreds of diehard militants from that patch in eastern Syria on the Iraq border.

The Syrian Observatory for Human Rights, a Britain-based monitor, said the alliance of Kurdish and Arab fighters was pressing on Monday in the face of tough obstacles.

“The SDF are advancing slowly in what remains of the Daesh pocket,” observatory chief Rami Abdel Rahman said.

But landmines, Daesh snipers, and tunnels the extremists have dug out for their defense are hindering the advance, he said.

SDF spokesman Mustafa Bali said there were “dozens of SDF hostages held by Daesh” inside their last foothold, but denied reports of executions.

The alliance has been battling to oust the militants from the eastern province of Deir El-Zor since September, backed by air power of the US-led coalition.

Screening for militants

Since December, tens of thousands of people, most women and children related to Daesh fighters, have fled to SDF territory.

US-backed forces near the village of Baghouz have screened the new arrivals, weeding out potential militants for questioning.

Another 600 people were able to reach SDF territory on Sunday after fleeing the fighting, the observatory said.

Among them, were 20 suspected Daesh members, including two French women, seven Turks, and three Ukrainians, said the monitor, which relies on sources inside Syria.

The SDF — which has said it expects the final offensive to be over in days — announced Sunday that it had taken some 40 positions from the militants following direct combat involving light weapons.

The alliance had earlier said that up to 600 militants as well as hundreds of civilians could remain inside a patch four square kilometers (one mile square).

Spokesman Bali said Daesh leader Abu Bakr Al-Baghdadi, the man who pronounced the cross-border “caliphate” in 2014, was not among them, and likely not in Syria.

At the height of their rule, the militants imposed their brutal interpretation of Islamic law on a territory roughly the size of Britain.

But military offensives in both countries, including by the SDF, have since retaken the vast bulk of their territory.

The militants however retain a presence in Syria’s vast Badia desert, and have claimed a series of deadly attacks in SDF-held areas. — AFP