MOSCOW (Sputnik) — Over a hundred of German citizens, including those with military training, have joined militias in eastern Ukraine to fight against Ukrainian government troops, Die Welt reported Sunday.

A research by Welt Am Sonntag has found that the majority of Germans swelling the ranks of anti-Kiev forces have USSR background. Some of them served with the Bundeswehr, known collectively as German armed forces.

A member of Chancellor Angela Merkel's ruling party, Stephan Mayer, told the newspaper German nationals who take part in civil wars should be taken to court. At present, the German criminal code only punishes those who fight alongside the brutal Islamic State (ISIL) terror group in Syria and Iraq.

Mayer also urged to strip those with dual citizenship of their German nationality and purposed criminal charges against Germans who go to war in eastern Ukraine.

The news was met with concern by Ukraine's ambassador in Berlin, Andriy Melnyk, who called on the federal government to stop its citizens from "travelling to the east to take part in the killings," Die Welt reported.

The United Nations estimates that the armed conflict in eastern Ukraine has killed more than 6,000 people, since it broke out in April 2014. Earlier this year, the Ukrainian government announced it was considering whether to ask the UN to deploy international peacekeepers to the region, but there was no formal request.