An ISIS fighter carries the ISIS flag inside the held territory

A young Belgian woman was detained at the country’s Charleroi airport on Sunday after being intercepted by Turkish authorities as she sought to return from Syria with her four-year-old son, officials said.

The woman, who left Belgium with her child and partner last year to go to Syria, was taken in for questioning upon her return, federal prosecutors said, adding that the police wanted to talk to her about her eight-month stay in the war-ravaged country.

It will then be up to an investigating judge to decide whether to take the case further, amid mounting fears in Europe over young people travelling to Syria to join jihadist groups.

Turkish authorities stopped the Belgian family on Thursday after they crossed the border from Syria. The woman and child were sent back to Belgium, while the man was remanded in custody in Turkey.

“There is an investigation ongoing in Turkey for her partner, who after all went to Syria and took part, it seems, in a number of training exercises including in the use of weapons,” Belgian Foreign Minister Didier Reynders was quoted as saying by public broadcaster RTBF.

“So it’s normal to look into what his role was. And we will then see if any investigations need to be carried out in Belgium as well.”

About the woman, the minister said: “There are certain questions she needs to be asked.”

French Prime Minister Manuel Valls on Sunday said as many as 10,000 Europeans could be waging jihad in Iraq and Syria by the end of this year.

Belgium is the European country that, relative to its population size, has produced the most jihadist fighters, with some 350 believed to have gone to fight in the Middle East for groups such as Islamic State.