An anticipated Syrian government offensive against rebels in Idlib province could displace more than 700,000 people, far more than were uprooted in a recent battle in the southwest of Syria, a U.N.-led group of health agencies said in a monthly report.
Many of Syria's battles have ended with agreements for fighters and their families to depart for Idlib governorate, where an influx of displaced people has roughly doubled the population to around 2.5 million.
The United Nations has said the province has become a "dumping ground" for evacuees.
The monthly Health Cluster Bulletin, published by a group of health-focused aid agencies led by the World Health Organization, said aid workers were bracing for the Idlib battle.
"Increased hostilities are expected in the North West in the coming period, to result in displacements of 250,000 to over 700,000 people in Idlib and surrounding areas," the report said.
"This will cause an increased need for humanitarian assistance to the new vulnerable and host communities, especially emergency health services."
Between mid-June and the end of July, 184,000 people were displaced by a battle in the south and subsequent agreements to end the fighting there. Among the displaced, more than 10,000 went to Idlib and northern Aleppo governorate, the report said.
The U.N. has repeatedly warned about the dangers of an attack on Idlib. Syria's President Bashar al-Assad said in a Russian media interview last month that Idlib governorate would be a priority for his forces.
U.N. regional humanitarian coordinator Panos Moumtzis said in June that the governorate's entire population of 2.5 million could be displaced and move towards the Turkish border if there was a major battle.
Such a battle would be much more complicated and brutal than anything seen so far in the seven-year war, he said.
The health cluster report included a map showing the breakdown of the population in southern and eastern parts of the governorate, suggesting that the displacement scenario was based on an attack by government forces from the south and east.
The map showed population estimates in four zones from the frontline up to the Latakia-Aleppo highway and the Hama-Aleppo highway, with a total of 993,000 people in those zones.