On September EU anti-terrorism chief Gilles de Kerchove said around 3,000 Europeans have joined the terrorist group ISIS, while CIA numbers put the total membership as high as 31,000 — three times greater than some early estimates. However today the condition are not so diffrent.

Hundreds of Germans have left their home country to fight alongside so-called “jihadists” in Syria and Iraq, Interior Minister Thomas de Maiziere said and Sweden's intelligence chief says the same story.

As many as 300 Swedes could have joined the ISIS insurgency, whose brutal tactics in Iraq and Syria have shocked the world, Sweden's intelligence chief said Saturday.

"A hundred cases of people who have left to join the fighting have been confirmed, then there are the presumed cases..., and then there are those that have not been counted, which brings the total to between 250 and 300," said the head of the intelligence services, Anders Thornberg, on SR public radio.

Thornberg said the flow of youths leaving to become "jihadists" in Syria was rapidly rising.

"We estimate 550. Just a few days ago we had 450," the minister told German television channel Phoenix on Friday. "These young people... were radicalized in Germany, within this society. That's why prevention must be accompanied by repression," Thomas de Maiziere German Interior Minister added.

De Maiziere said authorities are keeping a close watch on some 230 more people who are considered potential threats on German soil.

Concerns are mounting in Europe over the growing national security threat posed by “jihadists” returning from war-ravaged Syria and Iraq, although many European country like Germany announced new measures to prevent its citizens from travelling to join the terrorist group in Iraq and Syria.

Sweden intelligence services saying “the flow of youths leaving to become “jihadists” in Syria and Iraq are rapidly rising.

On their return to Sweden, some are seen as ready to commit terrorist acts at home and have been placed under strict surveillance, the intelligence official added.

In Britain it is estimated that Over 500 citizens have travelled to Syria. Prime Minister David Cameron has warned that militants could return to attack the West.

Today the head of London's police force said that as many as five terror plots were foiled this year, as he warned of increasing pressure on resources amid the rising threat.

Police have become increasingly concerned about young people traveling to fight in Syria and becoming radicalized by the ISIS group. The fear is that they will return and wage attacks at home.

Hogan-Howe's comments come as authorities prepare for a nationwide terrorism awareness campaign in which the police will attempt to build grass-roots support in a bid to prevent attacks. Briefings at some 80 venues such as schools, airports and shopping centers are planned.

But for some British Muslims, the path to "jihad" and the path to peaceful aid work can traverse much of the same terrain. From an office in Britain's second largest city, Waseem Iqbal and a friend are planning a trip to the Middle East.

In Jordan, they will bring food packages for Syrian refugees. Iqbal, 27, chose charity work not violence. "How do you save innocents in Syria? By going into a war zone and getting yourself killed? Or by... bringing people water pumps, schools and food packages? This is what saves innocents," he said.

Iqbal knows others who have taken a different path. Two acquaintances, young British men, were arrested and charged under Britain's terrorism laws. They were a world apart, Iqbal says, but they had one thing in common: anger.

For authorities struggling to prevent young Muslims from joining the wars in Syria and Iraq, understanding what drives these men is key.

In France it is appeared One of three Kalashnikov-wielding "Islamists" seen burning their French passports in an so-called "Islamic State" propaganda video this week grew up in a small village in southern France, the mayor said Saturday.

The 26-year-old, who goes by the name of Abou Ossama Al-Faranci in the Internet video, left the village of some 1,400 people five years ago, residents told the newspaper La Depeche du Midi.

The bearded blue-eyed man seen in the footage urging Muslims to stage attacks in France was reported to have gone to school in the village and have claimed converted to Islam, studying the Koran in a Muslim centre in a private home.

The Depeche du Midi daily said the man was thought to be married with two children. After moving to the southern city of Toulouse, he "left for Syria... about a year ago", it said.

French prosecutors on Thursday opened an investigation into the video showing the three Frenchmen. A source close to the inquiry said the trio had been identified.

A week ago another Frenchman, 22-year-old Maxime Hauchard, appeared in a grisly IS execution video.

Around 1,000 people from a wide range of backgrounds have left France to join jihadists in Iraq and Syria, with some 375 currently there.