RABAT (AFP) - A Moroccan man, with his two young French daughters in tow, was arrested in Casablanca Wednesday as he sought to join up with extremists of the Islamic State in Iraq and Syria (ISIS), authorities said.

The man identified by his initials N.R., who was under police restrictions in France, was picked up at Casablanca airport, the Moroccan interior ministry said in a statement.

He was detained along with his two girls, aged two and four, and a Moroccan woman with whom he had a "traditional" marriage, said the statement, cited by the local MAPP news agency.

His legal wife, a French national, was said to have remained in France.

The arrested couple will appear in court, while no mention was made of the way the children will be handled, or whether they will be returned to France.

The man was said to have been on his way to Turkey when he was arrested.

ISIS fighters are involved in heavy fighting just across the Turkish border in Syria.

Over 2,000 Moroccan Islamic extremists, including those with dual nationality, are currently fighting in Syria and Iraq, according to Rabat.

Moroccan authorities fear some will return and attempt to carry out attacks at home and has announced heightened security measures, notably at the borders.