Turkish soldiers and militia allies battled their way into a strategic Kurdish border town on Saturday as they stepped up their assault on northeastern Syria in defiance of mounting international protests and threats of US sanctions.
After overnight clashes with Kurdish forces in the countryside, Turkish troops and their Syrian allies entered the battleground town of Ras al-Ain, sources on both sides said.
Turkey's defence ministry hailed its forces' capture of the first Kurdish-held town on the fourth day of their offensive.
But Ras al-Ain's Kurdish defenders denied the semi-deserted town had fallen and an AFP correspondent said Turkish troops and their Syrian allies had entered but had yet to capture it.
The Kurdish-led Syrian Democratic Forces (SDF), who were the main partner on the ground in the US-led campaign against the Islamic State group, called on the United States to assume its "moral obligations" and protect them.
US President Donald Trump has faced a firestorm of criticism, even from his own domestic supporters, for abandoning a loyal ally and stands accused of giving Turkey a green light to launch the offensive after ordering American troops to pull back from the border.
The Syrian Observatory for Human Rights said pro-Ankara fighters "executed" at least nine civilians on Saturday near the town of Tal Abyad, another key target of the cross-border assault.
The Kurds said a female Kurdish party official and her driver were among those killed.
On the battlefield, SDF fighters have taken mounting losses against the vastly superior firepower of the Turkish army.
At least 23 SDF fighters have been killed, bringing the over death toll since the Turkish offensive began on Wednesday to 81, said the Syrian Observatory monitoring group.
Turkish air strikes on Kurdish-held towns and intense artillery exchanges caused mounting casualties on both sides of the border.
- Civilian exodus -
On the Syrian side at least 38 civilians have been killed, the Britain-based Observatory said, and 18 civilians inside Turkey have died from Kurdish shelling, according to Turkish reports.
Four Turkish soldiers have been killed, Turkey's defence ministry and state-run Anadolu news agency said, while the Observatory said the Kurds have lost control of 27 villages since Wednesday.
The towns of Ras al-Ain and Tal Abyad further west have been primary goals of the Turkish offensive and have both come under heavy bombardment.
They lie at either end of a section of the border which although Kurdish-controlled has an ethnic Arab majority.
Ankara says its forces' mission is to establish a safe zone run by its mainly Arab Syrian allies in which some of the 3.6 million mostly Arab refugees from Syria can be rehoused.
But the Kurds say the Turkish invasion amounts to an attempt to redraw the ethnic map of the region at their expense.
The operation has so far displaced some 100,000 people, according to the United Nations.
Roads leading out of the area have been filled with fleeing civilians, some on foot, other in vehicles piled high with their belongings.
"We always get displaced no matter where we go," Yusra al-Saleh, 38, who fled the violence along Syria's northern border, said.
The Kurdish Red Crescent said it would no longer dispatch medical teams to Ras al-Ain because its ambulances are being hit by Turkish fire.
Aid groups have warned of yet another humanitarian disaster in Syria's eight-year-old war if the offensive is not halted.
Most of those fleeing were heading east towards the city of Hasakeh.
"Turkey's aim is to prevent further fleeing Syrian civilians from entering Turkey rather than genuinely providing protection," Human Rights Watch.
The SDF lost 11,000 fighters in the protracted US-led campaign against IS before finally overrunning the jihadists' self-proclaimed "caliphate" in March.
- Trump warnings unheeded -
On Saturday, the SDF decried being "abandoned" by Washington. "We call on our allies to fulfil their duties and assume their moral obligations," it said.
The offensive has sparked international condemnation and Trump toughened his policy towards Ankara, threatening on Friday crippling sanctions if the operation goes too far.
On Saturday, Germany and France said they were halting sales of weapons to Turkey, after Paris, a key partner in the US-led anti-IS coalition, threatened sanctions against Ankara.
Arab foreign ministers, at an Arab League meeting in Cairo, joined in condemnation of Turkey's "aggression in Syria" they termed a "direct threat to Arab national security".
In Europe, thousands of people, many waving Kurdish green, red and yellow flags, took to the streets of Paris and several other cities in protest at the assault.
Turkish President Recep Tayyip Erdogan has remained defiant and the Pentagon has reported no progress in its belated efforts to persuade Ankara to halt the assault.
Turkey is still far from having reached the goals of its military invasion but the risk appears to be growing that detained IS fighters could break free.
Kurdish officials said five IS prisoners managed to escape Friday from a facility in the border city of Qamishli housing mostly foreign jihadists after shelling struck nearby.
The Kurdish administration says some 12,000 men are held in seven detention centres across Kurdish-controlled areas.
The US says it has already plucked two of the most high-profile IS jihadists to have been captured and spirited them out of Syria.