At least 125 foreign fighters, who had fought in lines of the PKK terrorist organization and its affiliates in Syria, have returned back to Germany, a report published by the German media has claimed.

Since the start of conflict in Syria, around 300 foreign fighters who were recruited in Germany have traveled to the region to join the PKK and its armed People's Protection Units (YPG), the Daily Express reported earlier this week.

According to the report, penned by Axel Spilcker, who cites security sources, the returning PKK terrorists received military training and took part in armed clashes.

While the PKK has been banned in Germany since 1993, the group has managed to set up several covert organizations and used them for its propaganda, recruitment and fundraising activities.

Hundreds of Westerners are believed to have joined and received weapons and explosives training from the YPG in Syria in recent years. The return of foreign fighters from the lines of the YPG will mean that the European authorities will have to find a way to deal with the radicalized, ideologically and militarily trained individuals who will be back to their homes in their respective societies.

A Turkish court on Tuesday placed a German national under arrest who was caught seeking to cross Turkey's southern border to fight with the YPG in Syria.

The man, aged 28, who has spent four years in the German military, was detained earlier in March seeking to cross the Silopi region in the Şırnak province that borders Syria and Iraq. Digital material and photographs that he had on him showed that he had been in contact with the terrorist group, reports said. According to Anadolu Agency (AA), the man had confessed to wanting to join the group in Syria. He has been charged with seeking "to aid and abet a terror group."

Turkey considers the YPG a terror group and the Syrian branch of the PKK. The PKK, which is listed as a terrorist organization by Turkey, the U.S. and the EU, has waged a terror campaign against Turkey for more than 30 years and has been responsible for the death of nearly 40,000 people.

But the YPG is seen by the U.S. and other Western powers as a partner against Daesh in Syria, despite the organizational and ideological links between the two.

Johannes Dimroth, spokesman of the Federal Interior Ministry, said Wednesday that the country's security agencies were taking all the necessary measures against the PKK's illegal activities.

"We are carefully monitoring the return of foreign fighters," he told a news conference in Berlin, but also added that they have not recently observed a significant increase compared to the previous years.

"But, of course, we take this phenomena very seriously," he added.

Dimroth said a total of 980 foreign fighters, including Daesh militants and other terrorists, are believed to have traveled from Germany to conflict areas in Syria and Iraq.

The terrorist group has nearly 14,000 followers in Germany, according to the latest annual report of the country's domestic intelligence agency.

The Europol report, entitled "EU Terrorism Situation & Trend Report (Te-Sat) 2017," says, "Belgium, France, Germany, Italy, Romania and Switzerland reported that the PKK continued its fundraising, propaganda and recruitment activities."

The Europol report adds that PKK has recruited its members among the Kurdish community in Italy, for activities in Europe or to be exported to conflict zones. In addition, the report adds that "Switzerland stated that the PKK were maybe running a number of ideological training camps for its youth in remote pre-Alpine areas during the second half of 2016."

Ankara has repeatedly made clear it has a zero tolerance policy toward foreigners who have fought with the YPG or who are seeking to join the group.

Two Czech nationals were sentenced last year to six years and three months behind bars in Turkey on charges of fighting for the YPG in Syria.

And former British soldier Joe Robinson, who had previously spent time in Syria with the YPG, was arrested last year while on holiday in Turkey after being recognized. He was later released on bail.