A 19-year-old main suspect was aiming to "kill himself and a large crowd at the concert either today or tomorrow," the head of the Directorate of State Security and Intelligence, Omar Haijawi-Pirchner, said.

The suspect, who is said to have North Macedonian roots, wanted to use the weapons outside the Ernst Happel Stadium to kill as many people as possible, Mr Haijawi-Pirchner said during a news conference on Thursday.

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He said the suspect was "clearly radicalised in the direction of the Islamic State (IS) and thinks it is right to kill infidels".

A blurred image of the man brandishing two large knives was also shown at the news conference.

A second suspect, said to be a 17-year-old Austrian citizen with a Turkish and Croatian background, had started a job at the concert venue days before the Taylor Swift shows were cancelled over the terror threat, according to officials.

He was employed a few days ago by a facilities company providing services at the venue during the concerts, according to officials. He was arrested by special police forces near the stadium.

The main suspect was also arrested.

No other suspects are being sought, Interior Minister Gerhard Karner said. However, a 15-year-old, who had been in contact with both suspects, was also questioned by police.

London 'going to carry on'

Policing minister Diana Johnson said Scotland Yard would look at "all the intelligence" ahead of Swift returning to the UK for a series of concerts next week.

The Metropolitan Police said there was nothing to indicate the events in Vienna would have an impact on Swift's upcoming show at London's Wembley Stadium, due to take place over five nights starting on 15 August.

But a spokesperson added: "As always, we will continue to keep any new information under careful review."

London Mayor Sadiq Khan said the city would "carry on" and host the events later this month.

When asked about the events in Austria, Mr Khan told Sky News: "We are a capital city, we are an international city, on a regular basis we host major events, whether it's concerts - Bruce Springsteen was most recently at Wembley Stadium - we're looking forward to welcoming Taylor Swift back.

"I'm currently at Stamford Bridge (Chelsea FC's stadium). Every other week, there's a game taking place. We have a huge amount of experience in policing these events, we're never complacent, many lessons were learnt after the awful Manchester Arena attack.

"I'm sure Vienna has got its own reasons to cancel the Taylor Swift concerts, we're going to carry on, working closely with police (and) ensuring that the Taylor Swift concerts can take place in London safely."

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'Preparatory actions'

Swift was due to play on Thursday, Friday, and Saturday, for an estimated 170,000 fans who had flocked to the Austrian capital from all over the world for the sold-out Eras Tour shows.

But event organiser Barracuda Music said in an Instagram post on Wednesday that "we have no choice but to cancel the three scheduled shows for everyone's safety" after "confirmation of [the] planned terrorist attack".

Swift, 34, has not yet commented on the cancellations.

Franz Ruf, director-general for public security at the interior ministry, said chemical substances and technical devices showing "concrete preparatory actions" were found at the 19-year-old's house in the town of Ternitz.

Internet evidence showed he had sworn allegiance to Islamic State's leader, the official added.

The suspects sought to use knives or homemade explosives as part of the alleged terror plot, AP news agency says, citing an official.

Authorities found Islamic State and al-Qaeda material at the home of the 17-year-old suspect.

Mr Ruf said authorities were aware of "preparatory actions" for a possible attack, and also that there is a focus by the 19-year-old perpetrator on the Taylor Swift concerts in Vienna," the Austria Press Agency reported.

The Kurier newspaper, citing sources familiar with the situation, reported that the suspect had stolen the chemicals from his workplace and had built a bomb.

The newspaper reported he had planned to drive a car into the crowd expected to gather outside the stadium, and had also considered using machetes and knives.

'Very serious'

Austrian Chancellor Karl Nehammer posted on X that "the cancellation of the Taylor Swift concerts by the organisers is a bitter disappointment for all fans in Austria.

"The situation surrounding the apparently planned terror attack in Vienna was very serious," he wrote.

But he added that, thanks to intensive cooperation between police and Austrian and foreign intelligence, "the threat could be recognised early on, tackled and a tragedy prevented".

Barracuda Music said "all tickets will be automatically refunded within the next 10 business days".

The same wording was posted under the Vienna dates on Swift's official website.