A BOMB threat in Gaggenau has sparked an evacuation just one day after a Turkish rally was cancelled as Ankara warned Germany to behave and threatened consequences for scrapping the event.German authorities in the southwestern town of Gaggenau evacuated the city hall after receiving a bomb threat, its mayor told German television, one day after he cancelled an event where Turkey's justice minister was to speak. The building has been evacuated and police are searching the city hall. The search is expected to take several hours. Asked by n-tv broadcaster if the bomb threat was linked to the cancellation, Gaggenau mayor Michael Pfeiffer said: "We presume this at the moment, but we don't know for sure. We presume there is a direct link."We don't know how seriously we should take this threat.” Police said they were called at around 8am local time following reports of a bomb threat. The area has been sealed off. The threat comes as Turkey told Germany it must "learn how to behave" if it wanted to maintain relations after Gaggenau and Cologne stopped Turkish ministers speaking at meetings of supporters of President Tayyip Erdogan. Gaggenau, a town in Rastatt in the south west of Germany, withdrew permission on Thursday for a meeting where Turkish minister Bekir Bozdag had been due to speak. The address would have been part of efforts to garner support among Germany's 1.5 million Turkish citizens for an April referendum on expanding Erdogan's presidential powers. City authorities said the meeting was cancelled due to a lack of space in the car park. Mr Bozdag cancelled a meeting with his German counterpart and flew back to Turkey. In Ankara, the Turkish foreign ministry summoned the German ambassador for an explanation, ministry sources said. Turkish Foreign Minister Mevlut Cavusoglu warned Germany of consequences of cancelling the event. He said that "if necessary we will give a response in every way", but did not elaborate when speaking to reporters in Ankara. The city of Cologne also blocked an event where Turkish Economy Minister Nihat Zeybecki was to speak on Sunday, amid security concerns.Mr Cavusoglu said: "The obstruction of meetings in Germany is a sign of how much Germany and the West are displaying double standards. "German officials say that when Turkish ministers come to Germany they must speak with German ministers. With such pressure we will not speak with you. "If you want to maintain relations with us, you have to learn how to behave. That is our message to Germany." Tensions between Berlin and Ankara escalated this week after Turkey arrested Deniz Yucel, a correspondent for the prominent German newspaper Die Welt. Germany said on Thursday the arrest, the first of a German correspondent under the crackdown that followed a failed July coup, had caused grave damage to ties.