ROME, Dec. 26 (Xinhua) -- Italian prosecutors have opened an investigation into a Moroccan-Italian woman who has been arrested by DIGOS anti-terrorism police, ANSA news agency reported Tuesday.

The 35-year-old woman, named only by the initials R.M., reportedly went to Syria with her three small children for the love of an extremist from the so-called Islamic State (IS) group, whom she had met online.

She was arrested at Milan's Malpensa airport on Dec. 23 on an international warrant from France, where the Italian father of her children lives and where he had reported her missing.

The woman, who is reportedly seven months pregnant, could face charges of international terrorism in Italy.

French prosecutors have accused her of criminal association with terrorist intent and of endangering her children.

Custody of the children has been awarded to their father, an Italian who works as a chef in a seaside resort in the south of France, ANSA reported.

Authorities tracked her down about a month ago, when she was expelled from Turkey on her way back from Syria and had to call the children's father to ask for help getting home.

French prosecutors will try to determine whether she brought the couple's children with her to Syria intending to draft them into IS child combat units, according to ANSA.

The woman has been incarcerated at Milan's San Vittore prison ahead of a Dec. 29 extradition hearing.

Returning foreign fighters, or Europeans who went to fight in IS ranks in Syria and Iraq, are considered a major terrorist threat now that IS has largely been militarily defeated.

"Foreign fighters are escaping, they are coming home," Interior Minister Marco Minniti told a police training academy a month ago.

"We are facing a military diaspora of return," he said in a speech posted on the ministry's official website.

Maximum international cooperation is essential to identifying and capturing these returning extremist fighters before they go into action at home, Minniti said.