Syrian Kurdish-led forces and Turkey have blamed each other over continued fighting despite a US-brokered ceasefire in north-eastern Syria.
The Kurds have appealed to American vice president Mike Pence to enforce the deal.
The Syrian Democratic Forces (SDF) said Turkey has failed to abide by the ceasefire, refusing to halt the siege of Ras al-Ayn, a key border town.
The group said that 30 hours after the five-day pause went into effect on Thursday, there were still reported clashes inside the town and medical personnel could not enter to help the wounded.
Turkish-backed Syrian fighters encircled Ras al-Ayn just before the ceasefire came into effect, trying to crush Kurdish resistance inside.
Throughout much of the day on Friday, fighting was reported there and in neighbouring villages which came under attack by the Turkish-backed forces.
The UK-based Syrian Observatory for Human Rights said Turkey-backed Syrian fighters have prevented a medical convoy from reaching Ras al-Ayn since Friday.
It said a medical convoy arrived outside the town but Turkey-backed factions closed the road ahead and behind, leaving it stuck outside Ras al-Ayn.
Turkey’s defence ministry said it was “completely abiding” by the accord.
It accused Kurdish-led fighters carried out 14 “attacks and harassments” the past 36 hours, most in Ras al-Ayn. It also said the Syrian Kurdish fighters used mortars, rockets, anti-aircraft and anti-tank heavy machine guns.
The ministry also said it was in “instant coordination” with the US to ensure the continuity of calm, excluding instances of “self-defence”.
The agreement – reached in negotiations between Turkish president Recep Tayyip Erdogan and US vice president Mike Pence — virtually hands Turkey its aims in the invasion, requiring Kurdish fighters to vacate a swath of territory in Syria along the Turkish border during the ceasefire.
The Kurdish-led force, which had only a nominal, indirect role in the deal, said it will abide by the halt in fighting but has not committed to any pull-out.
Mr Erdogan warned that Turkey will relaunch its assault on Tuesday when the deal runs out if the Kurdish fighters do not pull out of a zone 20 miles deep running the entire length of the border.
Turkish interior minister Suleyman Soylu said 41 suspected members of so-called Islamic State (IS) were re-captured after fleeing a detention camp amid fighting earlier this week in Syria. He said 195 other suspected IS members had already been re-taken.
Mr Erdogan has accused Syrian Kurdish forces of releasing some 750 IS members and families, amid Turkey’s offensive. The Kurds said they broke out of their camp a week ago, attacking guards, amid heavy clashes and Turkish air strikes nearby.
Turkey’s state-run English language broadcaster TRT World said the IS members and their families were captured by Turkey-backed Syrian opposition forces.
The foreign nationals, many of them Europeans, would be transferred to a Turkish-controlled zone in northern Aleppo, according to the broadcaster.