Belgium and other European states are preparing to evacuate citizens accused of having links to Islamic State from detention camps in north-eastern Syria through a newly declared safe zone being carved out by Turkish forces along the border.

Belgian officials informed family members of detainees held in two camps on Friday that they would attempt to take advantage of a five-day ceasefire to retrieve nationals allegedly tied to the terror group. The Guardian has learned that other European states, including France and Germany, are also looking at ways to take advantage of the window declared by US vice-president Mike Pence on Thursday to repatriate women and children.

Whether Britain is willing to re-examine its policy of largely ignoring its 30 or so nationals detained in Syria remains unclear, but the decision by allies to move quickly is likely to increase pressure on Whitehall to do the same. What to do with accused Isis fighters and their families has been a pressing global security concern in the wake of Donald Trump’s decision to suddenly withdraw all US forces from Syria, with fears that an ensuing vacuum could lead to a collapse of security at the four main camps.

Kurdish guards have already abandoned one detention centre, allowing up to 800 detainees, among them Isis members, to walk out. The French foreign minister, Jean-Yves Le Drian, said nine French women with alleged links to the group were among them. Two Britons are also thought to have fled.

NGO officials said detainees at the camp, known as Ain Issa, were mainly internally displaced, and those who had ties to the terror group were not radicalised.

“We’re talking about around 12,000 Syrians who live in the camp, the vast majority from Raqqa city or outskirts. The vast majority have been there for some time, more than a year or three years in some cases,” said Amjad Yamin, from Save the Children.

The ceasefire was aimed at forcing Kurdish groups to move back from the border. While the Kurdish force, known as the SDF, said it was withdrawing from the so-called safe zone declared by Turkey, the group’s leaders said they would not retreat from other parts of the province.

Instead, as part of a deal brokered on Sunday, the Kurds have agreed to Syrian regime forces returning to the north-eastern corner of the country – a factor that has added another layer of uncertainty to the question of Isis detainees, and likely prompted European states to act.

There were reports of sporadic shelling in the safe zone area, between the two border towns of Tel Abyad and Ras al-Ayn, but the ceasefire largely appeared to be holding on Friday. Turkey envisages that the area it has seized over the last 10 days will give it a buffer against Kurdish forces, with whom it has fought a long insurgency inside its own borders, and be a hub for Syrian Arabs currently exiled in Turkey, whom it wants to repatriate.

Another more immediate use for the area – to help solve the issue of Isis prisoners – had not been considered until late in the week. European states had shown little interest in retrieving foreign fighters, but have been exploring how to take back women and children. France has already repatriated about a dozen children. Some countries have said they would be prepared to do the same if mothers and their children made it to a consulate – a near impossibility without consular help.

During a visit to Baghdad on Thursday, Le Drian maintained that French women who joined the so-called caliphate should face justice in the region.

“The French women who went to this region in 2015 knew what they were doing,” he said. “They aren’t tourists. They are fighters against France and must face trial [in Iraq] if possible.”