Police in Peterborough are warning about fraudsters pretending to be from Thomas Cook.
A Facebook post this evening said: "We have received reports of calls purporting to be from Thomas Cook offering refunds and asking for bank details. Remember never give personal details to anyone over the telephone."
Action Fraud, the UK's national fraud reporting centre, wrote: "Criminals may use the #ThomasCook liquidation as an opportunity to target customers with requests for personal or financial details. Always be wary of any unsolicited messages or calls."
Thomas Cook, which has its head office in Lynch Wood, Peterborough, collapsed on Monday, leaving more than 1,000 city employees without a job.
Businesses and residents have reacted to the devastating news with a wide range of offers of support, including free sports tickets, hair cuts and taxi rides for job interviews, as well as free gifts and replacement holidays.
The Wonder Circus in Skegness is also now inviting Thomas Cook employees and their families to a night at the circus for free.
It said: "Just bring along some proof to the box office to show that you were an employee."