"Islamic State of Iraq and Syria" (ISIS) elements defending their last bastions in eastern Syria used the cover of bad weather to launch a vain but deadly counterattack against Kurdish-led fighters, AFP reported Tuesday (January 8th).

ISIS fighters were unable to hold on to the positions they attacked but the assault killed 23 members of the Syrian Democratic Forces (SDF) and also left nine extremists dead.

ISIS fighters took advantage of poor visibility to unleash suicide attackers on SDF forces along the front line in the Euphrates valley late on Sunday, the Syrian Observatory for Human Rights said Tuesday.

"Twenty-three SDF fighters were killed and nine ISIS extremists were also killed in fighting that lasted all night and into Monday morning," Observatory chief Rami Abdel Rahman said.

"On Monday morning, the SDF launched an offensive and retook all the positions they lost," the Observatory said.

"Due to its depleted manpower, ISIS was unable to hold on to the positions it attacked," it said.

Abdel Rahman said the extremists' defences in the area have collapsed and the end of the battle is near.