PARIS: About 10,000 civilians have fled to a camp just north of ISIS' bastion of Raqqa with hundreds more arriving each day as the battle for the city nears, Medecins Sans Frontieres (MSF) said on Thursday.

Residents are escaping Raqqa under cover of night as U.S.-backed forces close in, taking their chances against minefields and hostile fighters rather than risking death in a major battle expected to begin soon.

"It is not a massive exodus, but about 800 people a day are arriving in Ain Issa every day," Natalie Roberts, an emergency doctor from MSF France who had just returned from the region, told reporters.

The camp in Ain Issa village is run by the U.S.-backed Syrian Democratic Forces, which is made up predominantly of Kurdish fighters, who have now arrived to within 3 km (2 miles) of Raqqa and plan to press on with the assault on ISIS.

The SDF had planned to make the camp a transit point for civilians. But the need to register each person and with many not having an alternative destination to travel to, the camp has expanded to beyond its 6,000-person capacity, Roberts said.

Conditions have deteriorated especially due to the summer heat. The United Nations and other aid groups have yet to establish themselves in the zone, she said.

MSF is providing basic care including vaccinations, maternity care and treatment of chronic conditions. People with war wounds, mostly caused by mines, are being sent to three MSF hospitals further north.

It is unclear how many people remain in Raqqa, ISIS' Syrian base of operations for more than three years and a major symbol of the cross-border "caliphate" in Iraq and Syria. The city's population was estimated at 200,000 before the recent departures.

Roberts said that coalition bombing in Raqqa had appeared to be well targeted so far, but that the city's hospitals would not be equipped to handle the sort of injuries resulting from an intensification.