Failed AITO member Bents Bicycle & Walking Tours had 31 customers abroad when it ceased trading, the Civil Aviation Authority confirmed.
A further 100 people had booked to travel with the Shropshire-based specialist this month.
The CAA said all packages had been cancelled, but if passengers had scheduled flight tickets they may still use them ‘at their own risk’.
The company, which had an ATOL licence to carry 500 passengers a year, was formed 28 years ago by owner Stephen Bents.
All customers are being advised to contact the CAA for refunds and those who paid by credit card are being referred to their card issuer.
The CAA said those already on holiday would be able to continue with their trip and their return flights would still be valid.
