Taylor Swift has opened up about the "devastating" decision to cancel her Vienna shows - and said subsequent London shows were a "beautiful dream".

The US singer wrapped up the European leg of her Eras Tour at Wembley on Tuesday, describing the reaction from the sell-out crowds as a "giant bear hug".  But walking out on stage was a "rollercoaster of emotions", coming less than two weeks after three shows in the Austrian capital were cancelled over an alleged terror plot.

"The reason for the cancellations filled me with a new sense of fear, and a tremendous amount of guilt because so many people had planned on coming to those shows," she wrote in an Instagram post on Wednesday night.

"But I was also so grateful to the authorities because thanks to them, we were grieving concerts and not lives." She said she was "heartened" by the "love and unity" her fans showed in London over five shows this month.

All her energy had to go towards protecting the nearly half-a-million people coming to her London shows, she said, thanking stadium staff and authorities for their help.

She added: "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." "And then London felt like a beautiful dream sequence," Swift added.

"All five crowds at Wembley Stadium were bursting with passion, joy, and exuberance.

"The energy in that stadium was like the most giant bear hug from 92,000 people each night, and it brought me back to a place of carefree calm up there."

Since Swift last performed in the UK in June, the country was rocked by the fatal stabbing of three young girls at a Swift-themed dance class in Southport.

While the superstar did not acknowledge the horrific attack while on stage in London, she released a statement telling of her shock following the girls' deaths.

It's understood the singer has privately reached out to the families.