More than 50,000 people have fled twin offensives in Syria in recent days, as escalating violence is displacing large numbers of civilians across the country.
Around 30,000 left the northern majority Kurdish city of Afrin as Turkish and allied forces stepped up a siege.
In the Damascus suburb of Eastern Ghouta, some 20,000 have left rebel areas targeted by Syrian government forces.
On Friday alone, Turkish artillery fire killed 18 civilians in the city centre, where remaining residents were stocking up on food in preparation for a fully fledged siege.
Speaking from a makeshift clinic in southern Afrin, Dan Smith, a British volunteer medic with the YPG, told the Telegraph he had seen many casualties in the last few days.
“The situation just keeps getting worse, it’s a slaughter. They just bombed the civilian hospital,” Mr Smith, from London, said in a text message.
“We’ve treated men, women and children, mostly with air strike and artillery injuries."
Turkey’s military dropped flyers in Arabic and Kurdish on the northern Syrian town of Afrin yesterday morning, asking residents to stay away from "terrorist positions" and urging YPG militiamen to surrender.
The leaflets say Afrin civilians wanting to leave would be "under the guarantee" of the Turkish military. They urged Kurdish fighters to "trust the hand we extend to you," saying: "Come surrender! A calm and peaceful future awaits you in Afrin."
The seven-year war has displaced more than half of Syria’s 21 million population – six million inside Syria and another six million are seeking refuge outside the country.
The two offensives, one backed by Russia and the other led by Turkey, have shown how Syrian factions and their foreign allies are aggressively reshaping the map of control of the country as the UN looks on helplessly.
Turkey began its operation, codenamed Olive Branch, in January with the aim of clearing the YPG, which it sees as terrorists, from the border.
However, Turkish forces have continued deep into Afrin and threatened to continue on to Manbij, the next large town held by the Kurds. Recep Tayyip Erdogan, Turkey’s president, has previously claimed that Afrin was part of the Ottoman Empire and that the land should be returned to Arabs.
The foreign ministers of Turkey, Iran and Russia convened a meeting in the Kazakh capital Astana yesterday to discuss the situation in Syria. The three states last year agreed to contain the conflict on several fronts with "de-escalation zones", while simultaneously pursuing own military objectives in Syria.