This article is more than 11 months old

This article is more than 11 months old

Kurdish civilians have been fleeing key towns in north-eastern Syria as Turkish forces continue to bombard targets for a third consecutive day.

Donald Trump has also raised the possibility of imposing sanctions on Ankara. There were reports on Friday of airstrikes and shelling in Ras al-Ayn and Tel Abyad, the Kurdish-held towns that have borne the brunt of the fighting, as Turkish ground troops and their allies sought to close in on both.

What is the situation in north-eastern Syria? Read more

Thousands of civilians have fled from both towns as well as surrounding villages, and a camp of at least 4,000 displaced Syrians near Ras al-Ayn has been evacuated after Turkish artillery landed nearby, Kurdish administrators said.

The UN on Friday estimated that 100,000 people have fled from their homes in north-eastern Syria in the past few days, adding that a growing number had taken refuge in shelters and schools.

Turkey’s vice-president said on Friday evening that his country’s troops had advanced five miles into north-eastern Syria.

Kurdish activists reported at least one car bomb explosion outside a popular restaurant in the town of Qamishli on Friday afternoon, amid fears that Islamic State might use the fighting to launch its own attacks. A Kurdish media collective, the Rojava Information Centre, said one person was killed and no group has yet claimed responsibility.

Tel Abyad’s hospital was closed after most of its staff left, Médecins Sans Frontières said. “Our staff in Tel Abyad witnessed the town, that was once filled with life, become deserted,” said Robert Onus, the group’s emergency manager for Syria.

The US defence secretary, Mark Esper, told his Turkish counterpart to halt the offensive or risk “serious consequences for Turkey”, but it is unclear what effect that would have on a government in Ankara that believes it has the backing of the US president.

“While the secretary reaffirmed [that] we value our strategic bilateral relationship, this incursion risks serious consequences for Turkey,” Esper told Turkey’s defence minister, Hulusi Akar, in a phone call. Esper said Turkey’s actions posed a threat to US personnel stationed in Syria.

“As part of the call, Secretary Esper strongly encouraged Turkey to discontinue actions in north-eastern Syria in order to increase the possibility that the United States, Turkey and our partners could find a common way to de-escalate the situation before it becomes irreparable,” a Pentagon account of the call said.

About 64,000 people have fled Syria since the campaign began, according to the International Rescue Committee aid group. The Kurdish Red Crescent said on Thursday night that 11 civilians had been killed in the fighting, including an 11-year-old boy in Qamishli.

Clashes were reported overnight at different spots along the border, from Ain Diwar at the Iraqi frontier, to Kobane, more than 250 miles (400km) to the west.

Kurdish officials in al-Hawl camp, where around 400 guards watch over more than 60,000 female members of Isis and their children, claimed there were violent demonstrations on Friday morning which they characterised as a failed escape attempt. Such unrest has been frequent in the camp in recent months.

Play Video 4:04 What does Turkey's military action in northern Syria mean? – video explainer

The reports of the fighting, as well as concerns over the fate of about 11,000 detained Isis fighters and their families fuelled criticism of the Turkish offensive in Washington, where the president is under increasing pressure to lay down red lines for Ankara.

Trump’s abrupt decision on Sunday to clear US soldiers from the Turkish-Syrian border in effect gave Turkey a green light to attack the US-backed and Kurdish-dominated Syrian Democratic Forces (SDF). It has led to withering criticism from his allies in Congress, the evangelical movement and Israel.

Trump said on Thursday that he hoped he could mediate between Turkey and the SDF but kept open the possibility of doing “something very, very tough with respect to sanctions and other financial things” against Ankara.

A senior US official told the Guardian that certain Turkish actions could trigger sanctions.

“[Such actions] would include ethnic cleansing,” the official said. “It would include, in particular, indiscriminate artillery, air and other fire directed at civilian population. That is what we’re looking at right now. We have not seen significant examples of that so far.”

The French president, Emmanuel Macron, stressed the need to try to end Turkey’s escalating campaign in a phone call with Donald Trump late on Friday, Macron’s office said.

“France and the United States, which share common concerns, will coordinate closely in the coming days,” the Elysee Palace said in a statement.

The French foreign minister, Jean-Yves Le Drian, has called for an emergency meeting of the coalition of more than 30 countries created to fight Isis. France’s European affairs minister said next week’s EU summit would discuss sanctions on Turkey over its action in Syria.

The SDF remained in control of the camps and prisons holding Isis detainees and their families, a US state department official said.

Turkish defence officials claim their forces have killed 277 Kurdish militants, a figure that could not be verified. They have confirmed the death of two soldiers, the latest on Friday afternoon.