Recep Tayyip Erdoğan, the Turkish president, has said his country would “crush the heads” of Kurdish militants if they did not withdraw from a planned “safe zone” in northern Syria in time.

Speaking at an opening ceremony in the central Turkish province of Kayseri, Erdoğan said he would discuss the deployment of Syrian government forces in the safe zone during talks with Russia’s president, Vladimir Putin, next week, but warned Ankara would “implement its own plans” if a solution was not reached.

Following an intervention from the US, Turkey agreed on Thursday to pause its military offensive in north-eastern Syria for five days while Kurdish fighters withdrew from the safe zone.

Reports of Kurdish evacuation plans started to emerge on Saturday, with the Associated Press quoting senior Syrian Democratic Forces (SDF) official Redur Khalil as saying it planned to evacuate the town of Ras al-Ayn on Sunday. He said only after that would his forces pull back from a 120-km (75-mile) stretch between the towns of Ras al-Ayn and Tal-Aybad. He said he would also withdraw 30km (19 miles) from the border.

It is the first time Kurdish forces have publicly acknowledged they will withdraw from the border, saying they had coordinated it with the Americans. The agreement has not specified the area of its pullback.

On Sunday morning, the Turkish defence ministry said that a Turkish soldier had been killed and another wounded after an attack by the Syrian Kurdish YPG militia in Tal-Abyad. Earlier, both Turkish and Kurdish sides had blamed each other for fighting that has rattled the US-brokered ceasefire.

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Turkish-backed Syrian fighters clashed with Kurdish-led forces in several parts of north-eastern Syria on Saturday, with some crossing the border from Turkey to attack a village, a war monitor said.

Nearly two days into the five-day ceasefire, the two sides were still trading fire around Ras al-Ayn.

Turkey’s defence ministry said it was “completely abiding” by the accord and that it was in “instantaneous coordination” with Washington to ensure the continuity of calm. The ministry accused Kurdish-led fighters of carrying out 14 “attacks and harassments” in the past 36 hours, mostly in Ras al-Ayn, which was besieged by allied fighters before the ceasefire. It said Syrian-Kurdish fighters used mortars, rockets, anti-aircraft and anti-tank heavy machine guns.

The US, meanwhile, confirmed that the withdrawal of nearly 1,000 of its troops would continue, with personnel pulled out of Syria to be redeployed in western Iraq

En route to the Middle East on Saturday, the US defence secretary, Mark Esper, said: “The US withdrawal continues apace from north-eastern Syria ... we’re talking weeks not days. The current game plan is for those forces to reposition into western Iraq.”

Turkey also said it had recaptured 41 suspected Isis members who had fled a detention camp amid the chaos caused by the fighting earlier this week.

The Kurds, meanwhile, appealed to the US vice-president, Mike Pence, to enforce the deal saying Turkey has failed to abide by its provisions and has continued the siege of Ras al-Ayn.

The SDF said there were still clashes inside Ras al-Ayn and medical personnel could not enter to help the wounded.

The Britain-based Syrian Observatory for Human Rights said the Turkish-backed fighters entered Syria and advanced into Kurdish-held Shakariya, a village east of Ras al-Ayn where there were clashes and a Turkish strike a day earlier.

Video posted online showed the fighters driving alongside the wall Turkey has erected along the border and boasting that they were headed on “an assault” into Syria. The video did not show them crossing the border.

Syrian state media said Turkish-backed fighters also made an “infiltration attempt” south of Ras al-Ayn but were repelled in clashes with the Syrian government military that had just moved into the area. The reports gave no further details.

Quick guide What is happening in north-eastern Syria? Show Hide Who is in control in north-eastern Syria? Until Turkey launched its offensive there on 9 October, the region was controlled by the Syrian Democratic Forces (SDF), which comprises militia groups representing a range of ethnicities, though its backbone is Kurdish. Since the Turkish incursion, the SDF has lost much of its territory and appears to be losing its grip on key cities. On 13 October, Kurdish leaders agreed to allow Syrian regime forces to enter some cities to protect them from being captured by Turkey and its allies. The deal effectively hands over control of huge swathes of the region to Damascus. That leaves north-eastern Syria divided between Syrian regime forces, Syrian opposition militia and their Turkish allies, and areas still held by the SDF – for now. On 17 October Turkish president, Recep Tayyip Erdoğan, agreed with US vice-president Mike Pence, to suspend Ankara’s operation for five days in order to allow Kurdish troops to withdraw. The following week, on 22 October, Erdoğan and his Russian counterpart, Vladimir Putin agreed on the parameters of the proposed Turkish “safe zone” in Syria. How did the SDF come to control the region? Before the SDF was formed in 2015, the Kurds had created their own militias who mobilised during the Syrian civil war to defend Kurdish cities and villages and carve out what they hoped would eventually at least become a semi-autonomous province. In late 2014, the Kurds were struggling to fend off an Islamic State siege of Kobane, a major city under their control. With US support, including arms and airstrikes, the Kurds managed to beat back Isis and went on to win a string of victories against the radical militant group. Along the way the fighters absorbed non-Kurdish groups, changed their name to the SDF and grew to include 60,000 soldiers. Why does Turkey oppose the Kurds? For years, Turkey has watched the growing ties between the US and SDF with alarm. Significant numbers of the Kurds in the SDF were also members of the People’s Protection Units (YPG), an offshoot of the Kurdistan Workers’ party (PKK) that has fought an insurgency against the Turkish state for more than 35 years in which as many as 40,000 people have died. The PKK initially called for independence and now demands greater autonomy for Kurds inside Turkey. Turkey claims the PKK has continued to wage war on the Turkish state, even as it has assisted in the fight against Isis. The PKK is listed as a terrorist group by Turkey, the US, the UK, Nato and others and this has proved awkward for the US and its allies, who have chosen to downplay the SDF’s links to the PKK, preferring to focus on their shared objective of defeating Isis. What are Turkey’s objectives on its southern border? Turkey aims firstly to push the SDF away from its border, creating a 20-mile (32km) buffer zone that would have been jointly patrolled by Turkish and US troops until Trump’s recent announcement that American soldiers would withdraw from the region. Erdoğan has also said he would seek to relocate more than 1 million Syrian refugees in this “safe zone”, both removing them from his country (where their presence has started to create a backlash) and complicating the demographic mix in what he fears could become an autonomous Kurdish state on his border. How would a Turkish incursion impact on Isis? Nearly 11,000 Isis fighters, including almost 2,000 foreigners, and tens of thousands of their wives and children, are being held in detention camps and hastily fortified prisons across north-eastern Syria. SDF leaders have warned they cannot guarantee the security of these prisoners if they are forced to redeploy their forces to the frontlines of a war against Turkey. They also fear Isis could use the chaos of war to mount attacks to free their fighters or reclaim territory.

On 11 October, it was reported that at least five detained Isis fighters had escaped a prison in the region. Two days later, 750 foreign women affiliated to Isis and their children managed to break out of a secure annex in the Ain Issa camp for displaced people, according to SDF officials. It is unclear which detention sites the SDF still controls and the status of the prisoners inside. Michael Safi

The Observatory said Turkish-backed Syrian fighters had prevented a medical convoy from reaching Ras al-Ayn. It said the medical convoy arrived outside the town on Friday but Turkish-backed factions closed the road ahead and behind, leaving it stuck outside Ras al-Ayn.

The agreement – reached after negotiations between Erdoğan andPence – would virtually hand 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 said it was in contact with the Americans during the negotiations, said it would abide by the ceasefire but has not committed to any pull-out. Erdoğan warned on Friday that Turkey will relaunch its assault on Tuesday when the deal runs out if the Kurdish fighters do not pull out of a zone 30km (20-miles) deep running the entire length of the border.

On Saturday, the Turkish interior minister, Süleyman Soylu, said 41 suspected Isis members were recaptured after fleeing a detention camp amid fighting earlier this week in Syria. He said 195 further suspected Isis members had been recaptured, adding that they would be relocated to areas controlled by Turkey in northern Syria, including Afrin and al-Bab.

It was reported last week that after a Turkish shell landed near Ain Issa camp that holds members of Isis families, more than 700 managed to flee amid the chaos.

Turkey’s state-run English language broadcaster TRT World said the Isis members and families were captured by Turkish-backed Syrian opposition forces.

Erdoğan has accused Syrian Kurdish forces of releasing 750 Isis members and families, amid Turkey’s offensive. The Kurds say they broke out of their camp a week ago, attacking guards, amid heavy clashes and Turkish airstrikes nearby.