The Civil Aviation Authority (CAA) has put the amount still to be redeemed by holidaymakers who hold refund credit notes (RCNs) at £132 million.
The figure came to light as the CAA urged customers holding RCNs to use them before 30 September 2022, after which they will no longer be financially protected under the ATOL system.
The CAA added travel companies will no longer be able to issue ATOL-protected RCNs from 20 December this year.
CAA Head of ATOL Michael Budge said: “With over £130m of ATOL refund credit notes yet to be redeemed, and international travel opening up again, we want to remind consumers to redeem any unused credits to make sure they do not lose out.
“The decision to end the scheme reflects the changing of international travel restrictions with significantly increased demand from consumers over recent months due to the opening up of more destinations.”