The senior official told the German daily, Frankfurter Allgemeine Zeitung, that these extremists will pose serious threats to the country upon their return to their homeland as they have acquired new military knowledge and training from insurgents in Syria.

German authorities had previously confirmed the presence of some 20 citizens in Syria.

A recently published study reveals that between 2,000 and 5,500 foreign nationals are active in Syria. Senior counter-terrorism officials within the European Union have stated that at least 500 of those nationals come from the EU countries.

Pan-European police force Europol said in its annual EU Terrorism Situation and Trend Report released on April 25 that Syria was the “destination of choice for foreign fighters in 2012.”

The report cited the risk that the foreign fighters pose on Europe - after their return - through using new training and knowledge that they acquired in Syria for conducting terrorist activities.

“The threat from terrorism… remains strong in Europe. It also continues to evolve from structured groups and networks to smaller EU-based groups and solo terrorists or lone actors,” the report said.

Europe has seen a rise in the number of its citizens entering Syria as ‘jihadists.’

On April 24, EU’s anti-terror chief Gilles de Kerchove told the British media that some 500 Europeans were in Syria to fight against the government of President Bashar al-Assad.

Kerchove said Britain, Ireland and France were among the EU countries to have the highest numbers of militants in Syria.

Unrest has gripped Syria for over two years and the Syrian government maintains that the chaos is being orchestrated from outside the country.