The German government is facing calls to halt arms exports to Turkey after reports emerged that German-made Leopard tanks were being used in an offensive against the Kurdish YPG.
Some German politicians have requested that any moves to approve a tank upgrade deal be halted.
Turkish-led forces began an assault in Syria’s north-west on Saturday.
The row comes just weeks after the two countries’ foreign ministers vowed to improve bilateral ties.
Relations between the two Nato members have soured dramatically in recent years.
Reports on Friday suggested Berlin was moving to approve a request from Turkey for German arms manufacturer Rheinmetall to upgrade its Leopard 2 tanks, to make them less vulnerable to explosives.
The tanks are thought to have been used by Turkey against the Islamic State (IS) group in Syria. However, defence experts have claimed in German media that recent images from Turkey’s “Operation Olive Branch” appear to show them being used against Kurdish groups.