A speech by Turkish President, Abdullah Gul, at Berlin\'s Humboldt University was called off on Monday following an anonymous telephone bomb threat. Berlin Police was forced to evacuate the auditorium of the university because of a bomb alert, which it perceived to be serious ahead of Gul\'s speech on the history of Turkey\'s relations with Germany. \'We (the visitors) had to leave the lecture hall as quickly as possible. We could not even take our belongings,\' Sevim Ercan of the Berlin-based Turkish news website BerlinTuerk told IRNA. \'Numerous police vehicles cordoned off the area as special bomb squads combed through the building. The telephone connection was also cut off for a while,\' she added. Ercan said Gul\'s lecture would most likely be cancelled for good. According to Berlin police, the caller was difficult to understand but appeared to be threatening, and police had categorized the danger as serious. Gul arrived in Germany on Sunday for an official four-day visit in Germany.