At least 30 civilians have died as a result of Turkey's offensive in northern Syria, according to the UK-based Syrian Observatory for Human Rights.
It said 74 members of the Kurdish-led Syrian Democratic Forces (SDF) and 49 Syrian rebels aligned with Ankara had also been killed.
The observatory added eight Turkish soldiers had been killed but said Ankara had only acknowledged the death of five of them.
The UN estimated on Friday that 100,000 people had already been forced to flee their homes because of the conflict.
"Most are being sheltered in host communities but an increasing number of them are arriving at collective shelters in Al Hassakeh City and Tal Tamer (and) many are seeking refuge in schools," it said in a statement.
The intense fighting was concentrated around the border town of Ras al-Ayn on Saturday morning with the two warring parties both claiming to control the area.
Turkey, which launched its military incursion into Syria on Wednesday, argues it is necessary to create a "safe zone" along the border where it plans to relocate the more than three million refugees it is hosting. Furthermore, Ankara recognises the SDF-affiliated People's Protection Units (YPG) and the Kurdistan Worker's party — both Kurdish groups — to be terrorist organisations.
The Arab League joined the condemnation of Turkey on Saturday after gathering for an emergency meeting called by Egypt. The body's Secretary-General, Ahmed Aboul Gheit, called Ankara's offensive an "invasion of an Arab state's land and aggression of its sovereignty".
US Treasury Secretary Steven Mnuchin said on Friday that President Donald Trump had authorised US officials to draft "very significant" new sanctions to target Turkey after it launched its military operation, adding that banks were being notified.
EU member states including France, Germany and the UK have also condemned the military offensive but Turkish President Recep Tayyip Erdogan said on Friday that the country "will not stop it no matter what anyone says".
The Turkish Foreign Ministry also warned that it would retaliate against any sanctions.
"Turkey is fighting with terrorist organisations that create a threat to its national security," it said in a statement. "No one should doubt that we will retaliate ... to any step that will be taken against this."
Among the West's key concern is the fate of 12,000 fighters of the so-called Islamic State (IS) detained by Kurdish authorities in prisons and camps. Fears are that the hostilities will allow them to escape and regroup.