BEIRUT A U.S.-backed alliance of Syrian fighters including the Kurdish YPG militia captured an Islamic State-held town in Syria's northeast on Friday, the Syrian Observatory for Human Rights monitoring group said.
The capture of al-Shadadi in Hasaka province came three days after the beginning of an offensive against Islamic State in the area by the Syria Democratic Forces backed by U.S.-led air strikes, and would help isolate Raqqa, the jihadists' de-facto capital in Syria.
There was no immediate comment from the Syria Democratic Forces.
The Britain-based Observatory's director Rami Abdulrahman said al-Shadadi's capture was a "psychological blow" to the Islamic State group. He said it still controlled dozens of villages in the area, but that the SDF had taken many more villages and farmland in the past few days.
On Thursday the SDF announced it had launched an operation earlier in the week to seize al-Shadadi from Islamic State.
The U.S.-backed alliance, formed in October, includes the powerful YPG, which has proved the most effective partner against Islamic State on the ground in Syria for a Washington-led air campaign against the group there and in neighboring Iraq.
The SDF, which also includes Arab fighting groups such as Jaysh al-Thuwwar, captured areas of Hasaka from Islamic State late last year.
The YPG took swathes of territory from the group last year. Most of Hasaka province is under Kurdish control.
(Reporting by John Davison; Editing by Alison Williams)