A Syrian ceasefire brokered by Vice President Mike Pence in Turkey had already been broken by Friday morning as gunfire and shelling was heard in the border city of Ras al-Ayn.

The city, also known as Sari Kani, has been the centre of the majority of the fighting since Turkish President Erdogan invaded the country more than a week ago after President Trump ordered US troops to withdraw.

Amid outcry at home and abroad, Trump dispatched Pence to Ankara to end to the bloodshed - and a deal was announced that would see Turkey stop its attack while Kurdish forces withdraw from the border.

Smoke rises above the Syrian border city of Ras al-Ain on Friday, hours after a ceasefire was agreed in Turkey

While Kurdish leadership agreed to the deal it was far from clear whether individual armed militias - who fought and died to claim the territory from ISIS - would willingly hand it over to Erdogan.

On Friday, smoke billowed over Ras al-Ayn as gunfire and shelling could be heard inside the city, though it was unclear who was firing at whom.

Kurdish reports from inside the city claim SDF fighters have 'yet to respond' to targeting by Turkish mercenaries, Hawar News reported.

The ceasefire had earlier been praised by Trump, who said it would save 'millions of lives,' while Turkey cast it as a complete victory.

If implemented, the deal would achieve all the main objectives Turkey announced when it launched its assault on October 9: control of a strip of Syria more than 20 miles deep, with the SDF forces agreed to pull out.

Republican and Democratic senators have accused Trump of having betrayed the Kurdish allies who were vital in fighting Islamic State militants, of brushing aside the humanitarian costs of Turkey's invasion and of being outwitted by Ankara.

It was unclear what if any damage came from the shelling heard on Friday.

It was also unclear whether the Kurdish-led Syrian Democratic Forces (SDF) would fully comply with the agreement, which would leave Turkish forces in charge of a swathe of territory that the Kurds once held with U.S. military support.

Mazloum Abdi,

the commander of

the Kurdish-led Syrian Democratic Forces,

told Kurdish TV late on Thursday: 'We will do whatever we can for the success of the ceasefire agreement.'

The city, also known as Sari Kani, has been the centre of the majority of the fighting since Turkish President Erdogan invaded the country more than a week ago

Amid outcry at home and abroad, Trump dispatched Mike Pence to Ankara to end to the bloodshed on Thursday

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 swathe of territory that stretches about 60 miles along the middle of the Syrian-Turkish border, between Ras al-Ayn and Tal Abyad.

But forces are still entrenched in Ras al-Ayn, where they were fiercely battling Turkish-backed Syrian fighters trying to take the town on Thursday. Whether the Kurdish fighters pull out of Ras al-Ayn will be an early test of the accord.

The Kurds were US allies in the fight against the Islamic State but came under assault after Trump ordered US troops to pull out.

Trump framed the US-brokered ceasefire deal with Turkey as 'a great day for civilisation' but its effect was largely to mitigate a foreign policy crisis widely seen to be of his own making.

Speaking at a rally in Dallas on Thursday, the US president said he allowed Turkish and Kurdish forces to clash in deadly battles because the two sides were like children who needed to fight each other.

'It was unconventional what I did. I said they're going to have to fight a little while,' Trump said. 'Like two kids in a lot, you have got to let them fight and then you pull them apart.

'They fought for a few days and it was pretty vicious.'

More than 500 people have been killed including dozens of civilians, mostly on the Kurdish side, and 300,000 civilians have been displaced within Syria, according to the Syrian Observatory for Human Rights war monitor.