A US-backed Kurdish-Arab alliance on Sunday ousted ISIS from a bastion in northeastern Syria near the Iraqi border, it said.
The Syrian Democratic Forces, supported by US-led coalition air power, have been battling to expel the jihadists from the last villages they hold in eastern Syria.
“The SDF were able on Sunday to liberate Dashisha village” in the northeastern province of Hasakeh, the alliance said in a statement.
SDF fighters “are now just three kilometres (1.8 miles) from the Syrian-Iraqi border”, it said.
The Syrian Observatory for Human Rights, a Britain-based war monitor, said fighting for the village since Saturday had killed 30 jihadists.
Dashisha was an important ISIS bastion on a corridor linking jihadist-held territory in Syria and Iraq, Observatory head Rami Abdel Rahman said.
On Saturday, the Kurdish-Arab alliance seized the nearby village of Tal al-Shair from the jihadists, according to the Observatory.
ISIS fighters swept across large parts of Syria and neighbouring Iraq in 2014, declaring a so-called “caliphate” in areas they controlled.
But the jihadists have since lost much of that territory to various offensives -- in Syria to Russia-backed regime forces and to the SDF.
In early May, the SDF announced the final phase of its operation against the jihadists to expel them from their holdouts in Hasakeh and along the Euphrates River in the adjacent province of Deir Ezzor.
A senior Iraqi official said last month ISIS leader Abu Bakr al-Baghdadi was still alive and moving between jihadist-held areas in both provinces with a small group of followers.
In September, an US military chief said the jihadist leader was still alive and probably hiding in eastern Syria's Euphrates Valley.
Syria's war has evolved into a complex conflict involving jihadists and world powers since it started in 2011 with a vicious crackdown on anti-government protests.