The minors have been handed over to child protection services while the mothers will face judicial proceedings.
France has repatriated 35 French children and 16 mothers from camps in the northeast of Syria that hold family members of suspected ISIL (ISIS) armed group fighters.
The foreign affairs ministry said in a statement on Tuesday that the minors were handed over to child protection services while the mothers would face judicial proceedings.
Families and campaigners have long sought to draw attention to the plight of about 200 French children in Kurdish-run camps in Syria after they were either brought to ISIL territory by their parents or born there during the years of fighting.
One of the biggest and most overcrowded camps is al-Hol, where malnutrition and disease are rife and approximately two children die every week on average, according to a report by the Save the Children campaign group last September.
It was not immediately clear if any of the 51 recently repatriated people came from the camp.
Until now, France had refused to repatriate people in large numbers, arguing that its security concerns were paramount after a series of attacks from ISIL fighters, including the November 2015 assaults on Paris that left 130 people dead.
A piecemeal repatriation process of French children in Syrian refugee camps has continued since the ISIL group was expelled from its Syrian base in March 2019.
Before Tuesday’s operation, France had repatriated 126 children since 2016 under a policy that saw requests analysed on a slow-moving case-by-case basis.
In June 2020, France brought home 10 French children of ISIL fighters from a refugee camp in Syria.
The Syrian civil war started with peaceful protests against President Bashar al-Assad’s rule in March 2011 and developed into a multi-sided, protracted conflict that sucked in world powers.
The front lines have been mostly frozen for years but violence is continuing and millions of people remain displaced within Syria’s borders.
The UN human rights office said last month that 306,887 civilians had been killed in Syria during the conflict since 2011, about 1.5 percent of its pre-war population.