French authorities should promptly re-examine the request by the women's parents to let them return home, the court said, saying there had not been sufficient reviews to ensure against "arbitrariness" of the refusal.

But it did not issue a blanket ruling that all French citizens held in Kurdish-run camps in Syria since the fall of the Islamic State group should be repatriated, as requested by rights groups and Western allies including the United States.

"Neither domestic law nor international law required the state to act on behalf of its nationals and to repatriate them," said the court based in Strasbourg, eastern France.

It also acknowledged that the global fight against terrorism presents "new challenges in terms of security and defence in the fields of diplomatic and consular protection, international humanitarian law and international cooperation".

Ahead of a French review of the repatriation request, the court ordered the government to pay one set of parents 18,000 euros ($18,000) and the other 13,200 euros in damages and costs.

"France cannot forbid French citizens from its territory," said Marie Dose, a lawyer for one of parents.

- Security risks? -

Repatriations are hugely controversial in France, which has seen a wave of jihadist terror attacks since 2015 that have killed more than 250 people.

Other European countries such as Belgium and Germany have recovered most of their citizens who left to join the jihadist fight in Syria.

But the French government has long refused to return its citizens, saying jihadist fighters and their families would pose security risks.

Until last July, when 51 women and children were brought back from Syria, authorities had only returned a handful of women and children, including many orphans, on a "case by case" basis.

Earlier Wednesday, sources confirmed to AFP that one of the women was the widow of one of the jihadist attackers who stormed the Bataclan concert venue in Paris in November 2015.

She and the other women have been charged with associating with terrorists and imprisoned.

"We didn't wait for the ECHR decision to move forward," government spokesman Olivier Veran said after the ruling.

"We have already adapted the rules for examining the repatriation of French citizens still in northeast Syria. Each case, which at their core involve human beings, are subject to careful review," he said.

- Thousands of foreigners -

The case before the ECHR was filed by two couples who had pleaded with the French government directly and via courts for the return of their daughters, as well as grandchildren born after their arrival in Syria.

Both women were among hundreds of foreign nationals arrested and detained with their children after the defeat of the IS "caliphate" by Western-backed Kurdish forces in 2019.

The parents said they were held at least initially at the Al-Hol camp in northeast Syria, where rights groups have denounced harrowing sanitary conditions, malnutrition and overcrowding.

Since the detainees' health and lives were in danger, the parents argued that France had an obligation to return its citizens home, as ensured by articles in the European Convention on Human Rights.

The court agreed that "the general conditions in the camps had to be considered incompatible with applicable standards under international humanitarian law".

As a result, it said the French refusal should have been reviewed "by an independent body, separate from the executive authorities of the state", to ensure the decision was not arbitrary.

It also noted that the United Nations and other international bodies, as well as Syrian Kurdish forces themselves, have been urging European nations to repatriate citizens who left to join jihadists in Syria and Iraq.

On Monday, the head of the US armed forces' Central Command urged nations around the world to repatriate their citizens from Al-Hol, which holds some 56,000 people.

Most are Syrians or Iraqis, but an estimated 10,000 are wives and children of Islamic State group fighters from other countries, many of whom are still thought to be highly radicalised.