Sporadic clashes between Turkish forces and Kurdish groups were ongoing in a battleground Syrian border town on Friday, a monitor said, despite Ankara's announcement of a five-day truce.
"There are sporadic artillery strikes and you can hear shooting in the town of Ras al-Ain," said Rami Abdul Rahman, head of the Syrian Observatory for Human Rights.
He said both the Turkish military and its Syrian allies were involved in the fighting with the Kurdish-dominated Syrian Democratic Forces (SDF).
An AFP journalist on the Turkish side of the border heard artillery fire and saw clouds of smoke in several places inside Syrian territory.
Ras al-Ain has been a major goal of the Turkish offensive since its launch on October 9 but the town's Kurdish defenders have put up fierce resistance.
Turkey announced a 120-hour suspension of its offensive late Thursday, and Abdul Rahman said there was a lull in fighting in much of the rest of northeastern Syria.
The agreement - reached after hours of negotiations in Turkey's capital of Ankara between Turkish President Recep Tayyip Erdogan and US Vice President Mike Pence - requires the Kurdish fighters to vacate a swath of territory in Syria along the Turkish border. That largely solidifies the position Turkey has reached in its offensive, now in its tenth day.
The fighting Friday came even after the commander of Kurdish-led forces in Syria, Mazloum Abdi, told Kurdish TV late on Thursday: "We will do whatever we can for the success of the ceasefire agreement." But one Kurdish official, Razan Hiddo, declared that the Kurdish people would refuse to live under Turkish occupation.
Kurdish fighters have already been driven out of much - but not all - of a swath of territory that stretches about 100 kilometers (60 miles) along the middle of the Syrian-Turkish border, between Ras al-Ain and Tal Abyad.
But Kurdish forces are still entrenched in Ras al-Ain, where they were fiercely battling Turkish-backed Syrian fighters trying to take the town Thursday. Whether the Kurdish fighters pull out of Ras al-Ain will likely be an early test of the accord.
Turkish troops and their allied Syrian fighters launched the offensive two days after US President Donald Trump suddenly announced he was withdrawing American troops from the border area.
The Kurds were US allies in the fight against the ISIS group but came under assault after Trump ordered US troops to pull out.
Trump framed the US-brokered cease-fire deal with Turkey as "a great day for civilization" but its effect was largely to mitigate a foreign policy crisis widely seen to be of his own making.
Turkey considers the Kurdish fighters terrorists because of their links to outlawed Kurdish rebels fighting inside Turkey.