Austrian authorities have arrested a 19-year-old man for allegedly planning an Islamist attack in the Vienna region, in connection with concerts by US star Taylor Swift later this week.

The man, who had pledged his allegiance to the Islamic State (IS) group “in recent weeks”, was detained in Lower Austria about an hour from the capital early on Wednesday, Austria’s top security chief Franz Ruf told a press conference.

“We have established corresponding preparatory acts and also that there is a focus of the 19-year-old perpetrator on the Taylor Swift concerts in Vienna,” Ruf said.

The man, an Austrian citizen, is believed to have become radicalised on the internet. Ruf said that chemical substances had been seized at the suspect’s home and were being evaluated.

A second person believed to have been in contact with the suspect was arrested in Vienna.

Police measures will be stepped up in the Vienna region in the coming days, particularly at the entrances to the concerts of Taylor Swift who is performing on Thursday, Friday and Saturday in Vienna as part of her Eras tour.

About 65,000 spectators are expected for each show. Ruf said there would be a special focus among other things on entry checks and concertgoers should plan a bit more time.

Vienna police chief Gerhard Puerstl said the concrete danger had been minimised, but since there was still an “abstract danger”, necessary measures will be taken, with special units being deployed for the concerts.

In November 2020, a convicted Islamic State group sympathiser went on a shooting rampage in downtown Vienna, killing four and wounding 23 others before police shot him dead.

It marked the Alpine nation’s first deadly jihadist attack.