BEIRUT -- U.S.-backed opposition fighters led by Syrian Kurdish forces captured more territory from the Islamic State group in the northern town of Tabqa on Monday, pushing the extremists to northern neighbourhoods close to one of Syria's largest dams.
Tabqa is an important stronghold for the militants, located about 40 kilometres (25 miles) southeast of their de facto capital, Raqqa, and lies next to the IS-held Tabqa Dam on the Euphrates River.
The Kurdish-led Syrian Democratic Forces is the most effective ground force battling IS in Syria and will most likely lead the offensive to capture Raqqa in the near future.
A U.S. airlift of artillery and special forces advisers that placed them behind IS lines in March was a turning point in the Tabqa offensive and underscored the closeness between Washington and the SDF.
The Kurdish-led group said in a statement Monday that its fighters captured three more neighbourhoods in Tabqa, where they have been advancing since mid-April.
The Britain-based Syrian Observatory for Human Rights said IS fighters withdrew from the Tabqa neighbourhood known as Thawra City. It said Monday's fighting is concentrated in the only two remaining IS-held neighbourhoods, near the dam.
The Observatory said SDF fighters now control some 80 per cent of Tabqa. It added that 35 IS members have been killed there since Sunday.
The SDF is made up of several Arab, Kurdish, Turkmen and Christian groups that have captured wide areas of northern Syria from IS over the past year under the cover of U.S.-led coalition airstrikes. The largest and most powerful groups in the coalition are the main Kurdish militias known as the People's Protection Units, or YPG, and the Women's Protection Units, or YPJ.
NATO member Turkey carried out strikes against the YPG last week, killing at least 20 fighters. Ankara views the group as an extension of the Kurdish insurgency raging in southeastern Turkey and has threatened further military action.
The spiraling tensions led the U.S. to deploy troops along the Syrian-Turkish border as a way of preventing further violence between the two allies.
An SDF official meanwhile expressed optimism that the battle for Tabqa might be won in the coming hours.
"Daesh is retreating from most of Tabqa's neighbourhoods," Brig. Gen. Hussam al-Awwak, an Arab spokesman for the SDF, told The Associated Press by telephone, using an Arabic acronym for the extremist group.
"Daesh fighters are almost finished in Taqba," he said.
Elsewhere Syria, opposition activists reported government attacks on rebel-held areas, including eastern suburbs of Damascus, where rival insurgent groups have clashed recently.
The Observatory said airstrikes killed at least seven people on Monday, three in Saqba and four in Hamouriyeh. The Ghouta Media Center, an activist collective, said the airstrike on Hamouriyeh destroyed a three-story building, killing a woman and two children. It also reported the three killed in Saqba.
Opposition activists said an explosion in a rebel-held northern village on Sunday killed 13 people.
The Observatory said the blast in Awijel was either caused by a surface-to-surface missile or by an arms depot explosion, adding that five children and four women were among those killed. The Aleppo Media Center, an activist collective, said the missile attack killed 13, including children.
