The Syrian Democratic Forces (SDF) have seized a quarter of al-Raqa city from the "Islamic State of Iraq and Syria" (ISIS), AFP reported Monday (June 26th).

The Arab-Kurd alliance smashed into the group’s main Syrian bastion on June 6th after a months-long drive to encircle it.

"Since the offensive began, the SDF have captured around 25% of the city's built-up neighbourhoods," said Syrian Observatory for Human Rights head Rami Abdel Rahman.

Backed by coalition airstrikes, the SDF has fully seized the south-eastern districts of al-Meshleb and al-Senaa, as well as al-Rumaniya and Sabahiya in the west, he said.

From those neighbourhoods, they were bearing down on al-Raqa’s Old City in a pincer movement on Monday, with fighting raging in the western al-Qadisiya district and parts of the city's east.

SDF fighters also hold part of Division 17 -- a former Syrian army base -- and an adjacent sugar factory on the northern edges of the city.

"They want to cut off the city's northern part, including the Division 17 base, so that there is more pressure on ISIS in the city centre," Abdel Rahman said.