Man Returning from Mideast 'Combat Zones' Held at French Airport

A young man was detained Friday at an airport in southern France as he returned from Iraqi or Syrian "combat zones" via Turkey, a source close to the case said.

Aged "less than 20", the French national was on a wanted list and was immediately taken in for questioning by intelligence services after his arrest at Nice airport, the source added, without giving any further details as to whether the man is a suspected jihadist.

France is on high alert after Islamic State jihadists sowing terror in Iraq and Syria issued a call for Muslims to kill citizens from countries involved in a U.S.-led coalition fighting the extremists, "especially the spiteful and filthy French".

It is particularly concerned about nationals going to fight in the Middle East, amid fears they will return to commit attacks on home soil. Prime Minister Manuel Valls has said some 580 French citizens have gone to wage jihad in Syria, of which 189 have already come back.

But on Tuesday, authorities were left red-faced after a series of blunders saw three suspected jihadists walk free out of a French airport after being transferred from Turkish custody.

The government was spared further blushes after the men handed themselves over to police on Wednesday, and the trio are still in custody.

But the incident sparked concern at a time of high alert after the IS threat and the beheading of French national Herve Gourdel by jihadists in Algeria linked to the Islamic State group.

Authorities have since upped security in public places and on transport, and the foreign ministry has widened its vigilance alert for nationals abroad, from around 30 countries earlier this week to some 40 nations -- including Indonesia, Malaysia and the Philippines.