Chief of staff Peter Altmaier told the Funke Mediengruppe that Germany had the legal possibility of banning foreign politicians from entering the country.
“Just because the German government hasn’t used all of the means that international law puts at its disposal, that doesn’t give other countries a free pass,” he warned.
“A travel ban would be the last resort, and we are keeping it in reserve.”
Tensions between Berlin and Ankara have escalated dramatically since Turkey jailed the German-Turkish journalist Deniz Yücel in February on terrorism charges.
Since then several German cities have cancelled rallies set to be held by Turkish government ministers in the build-up to an April 16th referendum which would significantly increase the powers of President Recep Tayyip Erdogan.
Erdogan has responded by accusing Germany of “Nazi practices” and charging that Merkel has been harbouring terrorists.
Altmaier said that “we protest strongly against the Nazi comparisons and the grotesque accusations being made”.
“Turkey always places great value on defending the honour of its country. Germany also has honour,” he said, adding that post-war Germany was internationally recognized as a paradigm of the rule of law.