Taylor Swift says the cancellation of her Vienna tour dates over an attack threat filled her with "a new sense of fear".

In a post on Instagram, she said she felt "a tremendous amount of guilt" because so many people had planned on travelling to the shows.

Three concerts were cancelled in the Austrian capital earlier in August as three people were arrested in connection with allegedly planning attacks inspired by the Islamic State group.

The 34-year-old singer-songwriter finished the European leg of her Eras Tour on Tuesday at Wembley Stadium in London.

In a post on Instagram on Wednesday, the US singer wrote: "Having our Vienna shows cancelled was devastating.

"But I was also so grateful to the authorities because thanks to them, we were grieving concerts and not lives.

"I was heartened by the love and unity I saw in the fans who banded together."

She said the safety of her fans was paramount when continuing with her tour, adding: "I decided that all of my energy had to go toward helping to protect the nearly half a million people I had coming to see the shows in London.

"My team and I worked hand in hand with stadium staff and British authorities every day in pursuit of that goal, and I want to thank them for everything they did for us."

Explaining why she had chosen to wait until now to speak about the cancellation of the Vienna concerts, which were meant to take place between 8 and 10 August, she said: "Let me be very clear: I am not going to speak about something publicly if I think doing so might provoke those who would want to harm the fans who come to my shows.

"In cases like this one, ‘silence’ is actually showing restraint, and waiting to express yourself at a time when it’s right to.

"My priority was finishing our European tour safely, and it is with great relief that I can say we did that."

Swift performed eight concerts at Wembley this summer, overtaking a record for any solo singer, which was previously set by Michael Jackson in 1988.

Swift's next show as part of The Eras Tour is scheduled for 18 October in Miami, Florida.