US-backed militias have launched their final assault on Syria's Raqqa after a convoy of Islamic State fighters left the city, leaving only a hardcore of jihadists to mount a last stand.
"The battle will continue until the whole city is clean," said a statement by the Syrian Democratic Forces (SDF), a US-backed alliance of Kurdish and Arab militias.
The SDF said earlier that a group of the jihadists had left in a convoy taking some civilians with them as human shields. But there were conflicting accounts as to whether the evacuees included both Syrian and foreign fighters.
Raqqa's fall to the SDF now looks imminent after four months of battle.
"We still expect there to be difficult fighting," said Colonel Ryan Dillon, spokesman for the US-led international coalition backing the SDF in the war against Islamic State.
Raqqa was the first big Syrian city to fall to Islamic State as it declared a "caliphate" and rampaged through Syria and Iraq in 2014, becoming an operations centre for attacks abroad and the stage for some of its darkest atrocities.
But Islamic State has been in retreat for two years, losing swathes of territory in both countries and forced back into an ever-diminishing foothold along the Euphrates river valley.
"Last night, the final batch of fighters (who had agreed to leave) left the city," said Mostafa Bali, an SDF spokesman.
Bali described the civilians who left with Islamic State fighters in the convoy as human shields. The jihadists had refused to release them once they left the city as agreed, wanting to take them as far as their destination to guarantee their own safety, he said.
