Since 2018, armed militias with the support of Turkey have been "committing crimes under international law" in Afrin in northern Syria, the European Center for Constitutional and Human Rights (ECCHR) and Syrians for Truth and Justice (STJ) said in a statement.

The organisations have filed a criminal complaint with the German federal prosecutor's office, they said.

Syria has been plagued by civil war since 2011 when the government repressed peaceful protests, triggering a conflict that has killed more than 500,000 people and displaced millions.

Turkey has strongly supported the dissidents in the war and since 2016 has carried out successive ground operations to expel Kurdish forces from parts of northern Syria.

Turkey and its Syrian rebel proxies seized Afrin in a 2018 offensive that drove Kurdish-led fighters -- and much of the resident Kurdish civilian population -- from the area.

"Afrin's population, and especially its Kurdish citizens, have faced widespread and systematic violations since 2018," said Bassam Alahmad, executive director of STJ.

"These abuses range from forced disappearances, arbitrary arrests and torture, to sexual violence," he said.

Germany has in the past repeatedly prosecuted atrocities committed abroad, including in Syria.

It does so using the legal principle of universal jurisdiction -- which allows countries to try people for crimes of exceptional gravity, including war crimes and genocide, even if they were committed in a different country.

One of the most high profile cases to be brought to trial was that of a former Syrian colonel who was found guilty in January 2022 of crimes against humanity committed in Damascus.

Other such cases have also sprung up against Syrian government forces in Germany, France and Sweden.

"However, the suffering experienced by the predominantly Kurdish civilian population in north-western Syria has not yet been addressed," the organisations said.