The two nations have been at loggerheads for months after the jailing of a German reporter by Ankara.
Turkish ministers were then banned from rallying in Germany and were even turned around when they attempted to boost Erdogan’s power referendum votes.
An explosive row followed as President Erdogan subsequently accused Germany of ‘Nazi tactics’ and state-run media ran pictures of Chancellor Angela Merkel dressed as Hitler.
The feud had, according to both sides, ended, but according to German media the bitter war is being waged behind closed doors.
President Recep Tayyip Erdogan has requested taking time at the G20 in Hamburg so he can talk to his supporters – yet he will be blocked by Mrs Merkel’s team.
Foreign Minister Sigmar Gabriel, speaking in Krasnodar said: “We have had an official request from Turkey yesterday to tell us that Turkish President Erdogan wants to talk to his fellow countrymen at the G20 summit.
“At the moment, such performances are not useful.”
He also said a speech from Ankara “does not fit into the political landscape”.
Turkish Foreign Minister Cavusoglu allegedly made the request weeks ago but the federal government wants to prevent all non-EU politicians speaking in Germany three months ahead of Bundestag elections.
Government spokesman Steffen Seibert said: “What Minister Gabriel said about this was in accordance with the Federal Chancellor. Therefore it is the opinion of the federal government.”
Germany is a massive influencing factor in the controversial one-for-one migration deal, which sees Ankara taking control of migrants and cutting off the Aegean route to Europe, in return for £4bn from brussels.
Since Germany is the end destination for most fleeing Syria, Iraq and Afghanistan, Berlin was keen to get the deal going.
But after the row it is on the brink of collapse, with reports of crossings picking up once more.
Last spring Turkish Foreign Minister Mevlüt Cavusoglu had to do his speech from the balcony of the Turkish consulate in Hamburg.
The fall-out was huge, with politicians from both sides squaring up -with the migration deal in the middle.
Turkey later threatened to release all 4million it currently golds to the European Union
The last appearance of Erdogan in front of supporters in Germany took place in Karlsruhe in May 2015.