Denmark has revealed plans to push through an urgent bill that would allow the government to strip Danish citizenship from dual nationals who have left the country to fight with militant groups abroad.
In a statement released Monday, the government cited a "significant risk" from fighters who left to joined the so-called Islamic State (IS) group and who may now try to return to Denmark.
The decision to accelerate the legislation comes as a result of Turkey's military operation against Kurdish-controlled areas in northern Syria, where the Kurds also oversee a number of camps housing IS prisoners.
"There is a risk that the Kurdish-controlled IS camps in the border area will collapse, and that foreign warriors with Danish citizenship will move toward Denmark," the country's Prime Minister Mette Frederiksen said.
She added: "These are people who have turned their backs on Denmark and fought with violence against our democracy and freedom. They pose a threat to our security. They are undesirable in Denmark.
"The government will therefore do everything possible to prevent them from returning to Denmark."
Authorities believe at least 158 people from Denmark have joined militant Islamist groups in Syria or Iraq since 2012, about 27 of whom remain in the conflict zone. Twelve of these are believed to be imprisoned.
All 27 are Danish nationals but it is unclear how many of those have dual citizenship.
Europeans comprise a fifth of around 10,000 Islamic State fighters held captive in Syria by Kurdish militias which are now under heavy attack by Turkish forces. If the militias redeploy prison guards to the front line, there is a risk of jail-breaks.
The proposed new law, which has broad support among lawmakers of different parties, would allow the government to strip fighters abroad who also hold another nationality of their Danish citizenship without a court order.
The law would not apply to single nationality Danes who could be left stateless.
Other European countries have also said they will strip dual nationals who joined Islamic State of citizenship.
They are reluctant to try such foreign fighters at home, fearing a public backlash, difficulties in collating evidence against them, and the risk of renewed attacks by militants on European soil.