Turkey on Monday said it had deported an American and a Danish citizen accused of belonging to ISIS, as it began repatriating foreign fighters to their home nations.
Germany confirmed that one of its citizens was also expelled, and seven other German nationals were due to leave the country on Thursday, Ismail Catakli, spokesman for the Turkish Foreign Ministry, told the state-run Anadolu news agency.
Two Irish nationals and 11 Frenchmen who were captured in Syria were also due to be flown to their home countries soon, he added.
In all, more than 20 Europeans are still in the process of being deported.
The Danish national was arrested on arrival at Copenhagen airport after being deported on Monday and Copenhagen police said the man had already been sentenced to four years in prison for joining ISIS.
But there was confusion over the fate of the US citizen, with Greece saying that Turkey had tried to deport him over their shared border.
Greek police said they rejected the man and sent him back to Turkey. Images showed him temporarily trapped between the two borders early on Monday.
A State Department official said that US authorities "are aware of reports of the detainment of a US citizen by Turkish authorities" but could not comment further because of privacy rules.
There are 813 militants being held at 12 deportation centres in Turkey, state broadcaster TRT Haber reported.
Suleyman Soylu, the Turkish Interior Minister, said about 1,200 foreign ISIS fighters were in Turkish prisons and 287 members, including women and children, were recaptured during Turkey’s military offensive into north-east Syria last month.
Turkey, which is facing claims that it has not actively pursued ISIS suspects, has criticised western states for refusing to take back citizens who fought with the terrorist group.
European nations have sought to extradite suspects to Iraq to face trial there rather.
There are concerns that the prosecution of suspects under European laws would be difficult and sentences would be short.
France particularly has sought to have its nationals tried in Baghdad and is pushing to set up a European fund to cover the costs on behalf of the Iraqi state.
The UK has stripped several high-profile ISIS suspects of British citizenship and issued temporary exclusion orders to stop them trying to return to the UK.
London insists suspects should be tried by the countries in which their crimes were committed, mostly in Iraq and Syria.
But Turkey is now pledging to send back ISIS suspects even if their citizenship has been revoked.
Most of those captured managed to escape from Kurdish detention when guards were sent to fight against the Turkish incursion.
Turkey launched the offensive against the Kurdish YPG militia last month after a decision by US President Donald Trump to withdraw troops from the region.
The move prompted widespread concern over the fate of ISIS prisoners.
The YPG is the main element of the Syrian Democratic Forces, which has been a leading US ally in beating back ISIS.
It kept thousands of militants and ISIS supporters in jails and detention camps across north-east Syria.
Turkey’s move to transfer ISIS foreign militants comes amid Ankara’s frustration with western nations that refused to back its offensive.
Ankara considers Kurdish militias to be terrorists because of their links to the Kurdistan Workers’ Party, which has been waging an insurgency in Turkey since 1984.
Its offensive angered Washington and Turkey's main European Nato allies.
There has yet to be any confirmation from the US about the deportation, or comments from other countries that may have been approached by Turkey about repatriation of their citizens.
Meanwhile, three French women who escaped from a camp for suspected militants in northern Syria say they want to go home and face whatever legal action Paris hands out over their links to ISIS.
The three are in Syria's Suluk town, which is under the control of Syrian rebels backed by Turkey.
They said they fled during the chaos of Ankara's incursion last month and turned themselves over to Turkish troops, hoping to go home.
The women suggested they were prepared to go France for the sake of their children, and said conditions in the camp in Ain Issa, run by the SDF, were very hard.
They gave no details of their lives before detention.
They are believed to be among the wives and children of former ISIS fighters killed or detained after the militant group was expelled from its strongholds in Iraq and Syria.
"We want to go back for our children to go on with their lives," one of the women said.
"I’ve been here for five years and I want to go back and go on with my life, go back to the time I lost. That's it.”
A second woman said she wanted to return to France quickly and whatever the French courts decided was "not a problem".
"Children got sick very quickly," she said. "There was not much to eat. I want to go back to France with my son."
A third woman said: "We have no problems with a ruling in France. It is for that reason that we handed ourselves over to the Turks, to go back to our country."