The legal initiative backed by the Berlin-based European Center for Constitutional and Human Rights (ECCHR), targeted six high-level figures by name plus a number of unidentified officials in Syrian military intelligence.

"The claimants were tortured or witnessed torture in the prisons of the intelligence services,” Wolfgang Kaleck, secretary general of the ECCHR, said on Thursday.

"The aim of this criminal complaint is the issue of international arrest warrants and the beginning of investigations by the prosecutor's office with respect to the persons identified as responsible for the committed crimes,” he added.

Germany's "code of crimes against international law" allows for the filing of lawsuits against war crimes suspects and in cases of crimes against humanity committed abroad, irrespective of the citizenship of the victims or the perpetrators.

Syrian lawyer Anwar al-Bunni expressed hope the German federal prosecutor would open a formal investigation following their complaint.

"Massive human rights violations must not remain unanswered; this is clear since the Nuremberg trials. Torture is absolutely forbidden. Germany has to send a signal,” he said.

The Assad regime is widely seen as being responsible for systematic torture targeting thousands of opponents and activists.

Syria has been locked in a devastating civil war since early 2011, when the regime cracked down on pro-democracy protests -- which erupted as part of the "Arab Spring" uprisings -- with unexpected ferocity.

Since then, hundreds of thousands of people are believed to have been killed and millions more displaced by the conflict.

Anadolu Agency