The Kurdish-led Syrian Democratic Forces were a key US ally in the war against the Islamic State group and drove the extremists from most of the territory they once held in northeastern Syria.
US President Donald Trump has been accused of abandoning a loyal ally and giving Turkey a green light to launch the long-threatened offensive after ordering American troops to pull back from the border.
The US withdrew its troops from the Syrian border region last week, paving the way for the Turkish operation.
Hervin Khalaf, secretary general of the Future Syria Party, was ambushed south of Tal Abyad in northern Syria, in an attack the SDF blamed on Syrian National Army fighters.
Local residents applaud as a convoy of Turkish forces trucks transporting tanks is driven in Sanliurfa province, southeastern Turkey, at the border with Syria, Saturday, Oct. 12, 2019.
Fighting on the Syrian border with Turkey has prevented the SDF from securing IS detention camps in areas under its control, senior official Redur Xelil said in a televised statement on Saturday.
On Wednesday, Turkey launched an offensive Northern Syria after the withdrawal of the USA forces leaving their former ally, the Syrian Democratic Forces (SDF), in a deadly confrontation.
The Kurdish-led Syrian Democratic Forces (SDF), in which the YPG comprises the main fighting element, denied losing the center of Ras al Ain.
"We are fully aware that government which dislike Turkey's advocacy for Palestinians, objections against handing over Jerusalem to occupiers and calling things as we see them -including coups, murders, and the bombardment of civilians in Yemen- do not speak for the Arab world", Altun said.
But the Kurds say the Turkish invasion amounts to an attempt to redraw the ethnic map of the region at their expense.
The assault has raised worldwide alarm over its mass displacement of civilians and the potential for Islamic State militants escaping from Kurdish prisons resulting in a revival of the jihadist group's insurgency in Syria.
Navy Captain Brook DeWalt said the area was "known by the Turks to have United States forces present".
He has said he would like the U.S. to negotiate a truce between North Atlantic Treaty Organisation ally Turkey and the Kurds. However, there is a risk they may flee amid the offensive while the SDF are fending for themselves, trying to repulse multiple ground attacks along a roughly 120-kilometre (75-mile) stretch of the border.
"We don't mediate, negotiate with terrorists". The top of the Arab League denounced the operation and British Prime Minister Boris Johnson spoke to Turkish President Tayyip Erdogan to precise his "grave concern" concerning the offensive.
In its first big attack since the assault began, IS claimed responsibility for a deadly vehicle bomb in Qamishli, the largest city in the Kurdish-held area.
Thousands of people, some shouting "Erdogan terrorist", took to the streets of Paris and other European cities on Saturday in protest at the Turkish assault on Kurds in Syria.