The Syrian Democratic Forces (SDF) have ousted "Islamic State of Iraq and Syria" (ISIS) from half of the group's Syrian bastion al-Raqa, AFP reported Wednesday (July 26th).

The SDF "are now in control of 50% of al-Raqa city despite the fierce resistance mounted by ISIS", Rami Abdel Rahman, head of the Syrian Observatory for Human Rights, said.

The SDF assault has been backed by airstrikes, special forces advisers, equipment and weapons from the international coalition fighting ISIS in Syria and neighbouring Iraq.

The spokeswoman for the SDF's al-Raqa operation said that just under half the city was under SDF control.

"Forty-five percent of al-Raqa has been liberated. Our forces are advancing on all sides," Jihan Sheikh Ahmed said late Wednesday.

"The tighter the noose grows around ISIS, the more strongly it reacts and the tougher it fights," Ahmed said.

ISIS first seized al-Raqa in early 2014, and the city has since become synonymous with the group's most gruesome atrocities.

The extremists carried out public beheadings there and are also thought to have used al-Raqa as a hub for planning attacks overseas.

Once ISIS is ousted from al-Raqa, a body called the al-Raqa Civil Council is expected to run the city's administrative affairs.