Three concerts by American singer Taylor Swift in Vienna, scheduled to take place on Thursday, Friday and Saturday, have been cancelled after two persons were detained on suspicion of the preparation of terrorist attacks in the Austrian capital.

"In connection with the confirmation by officials of a planned terrorist attack at the Ernst Happel Stadium, we have no choice but to cancel the three planned concerts for the sake of everyone's safety. All tickets will be refunded within 10 working days," the local organizers, Barracuda Music, said in a statement.

Earlier, head of the Austrian Interior Ministry's Public Security Department Franz Ruf stated that a 19-year-old Austrian citizen had been detained in the city of Ternitz on suspicion of preparing the attacks. Another person was detained in Vienna, but authorities did not provide any information about him.

"We have established that appropriate preparatory actions were in place and that the 19-year-old suspect was targeting Taylor Swift's concerts in Vienna. "According to the investigation, both suspects were radicalized online," Roof said. He said the 19-year-old “pledged allegiance to the Islamic State group in early July.”

Roof also said chemicals were seized from the suspect's home and sent for testing.