Islamic State militants are putting up a desperate fight against advances by US-backed Syrian forces.
A commander with the Syrian Democratic Forces said the extremists have staged a counter-attack from the tiny speck of land they still hold in eastern Syria.
He said the IS offensive began overnight, from the west of a riverside pocket in the Syrian village of Baghouz where the Islamic State group has been making its last stand.
He said that the Kurdish-led forces are repelling the IS counter-attack.
A spokesman for the US-backed forces, Adnan Afrin, said IS militants are putting up a “fierce resistance”, firing mortar shells and rocket-propelled grenades.
The battle to retake Baghouz and surrounding villages began in September.
For the last few weeks, the militants remained holed up in the shrinking space along the eastern banks of the Euphrates River.
Since early February, more than 10,000 civilians were evacuated from the IS-held pocket, most of them family members of IS fighters.
The capture of Baghouz would be a milestone in the four-year campaign to defeat IS’s so-called “caliphate,” which once covered a vast territory straddling both Syria and Iraq.
The US-led coalition said it was continuing strikes against IS positions “day and night”, allowing the militants no freedom of movement.
“Combined with the SDF ground movement, the final push in (Baghouz) continues,” the coalition said.