LONDON (Reuters) - Insurers face millions of dollars in claims after a foiled attack forced three Taylor Swift concerts in Austria to be cancelled, though several providers will share out the hit, two people involved in insurance for her tour told Reuters.

The concerts in Vienna were cancelled this week after a planned attack at the Ernst Happel Stadium. Some 195,000 "Swifties" had been expected to attend, with many travelling from abroad for a chance to see the pop superstar.

Barracuda Music, the concert organiser, said all tickets would be refunded within 10 days. It could not immediately be reached for comment about insurance arrangements.

Swift is popular among insurers as she rarely cancels concerts, a third insurance source said. Her celebrity and success mean that most specialist event cancellation insurers in London would be involved in covering her tour, one of the sources said. The sources declined to be named, citing client confidentiality.

Organisers of large sporting and entertainment events typically buy event cancellation insurance, much of which tends to be insured through the Lloyd's of London market by a consortium of insurers.

A Lloyd's of London spokesperson confirmed that event cancellation insurance is offered at Lloyd's, but said it could not comment on specific policies.

Militant attacks are often excluded from event cancellation policies, but policyholders typically buy extra cover against them, or the threat of them."The standalone terrorism cancellation insurance policy would have been triggered by the terrorism act or threat clause within the policy, as there has been a known potential terrorism event," said Tim Thornhill, managing director at broker Tysers.

Reuters could not establish the extent of cover on the concerts. Marcos Alvarez, managing director for global financial institution ratings at Morningstar DBRS, said losses from the cancellations could be in the tens of millions of dollars.

Alvarez said insurance losses were likely to be limited by the fact that the concerts could be rescheduled.

The cover was structured so that insurers would not be on the hook for a full cancellation of the tour, said Andrew Colcomb, head of syndicate research at Argenta Private Capital, based on his analysis.

Swift's Eras tour is estimated to generate nearly $2 billion in ticket sales.

Event cancellation insurance typically also covers delay, moving the event to another location, rent for the venue, the artist's pay and ticketing.

The policies can be taken out by local or international organisers, and artists can add their own policies to make sure they get paid for the event if it is cancelled, industry sources say. The stadium would also typically have event cancellation insurance, said Loretta Worters, vice president, media relations at the U.S. Insurance Information Institute.

"Assuming this is an isolated event, we believe that most insurers will remain comfortable with their exposure to cancellation insurance products," Alvarez said.

Going forward, he added: "insurers could restrict the coverage available for cancellation insurance due to terrorism, given increasing political tensions around the world".

Leigh Ann Rossi, senior vice president, sports and entertainment group, at broker NFP, also said she didn't think "this one-off concert claim will move the needle in the marketplace".

She added, however, that "should this become a pattern or if something happens in Paris at the Olympics, these could have impact on the marketplace".

British police said on Thursday there was nothing to indicate the planned attack would have any impact on Swift's return next week to Wembley Stadium, London, for her five final shows in Europe.

Any extra security for the concerts would "create a significant challenge" for the police, said Rich Phillips, head of crisis, resilience and reputation consulting at insurance broker Marsh, particularly as officials are on high alert after days of rioting in Britain involving racist attacks targeting Muslims and migrants.