Asia specialist Gendai Travel, which owned several brands including Japan Travel Centre and JTC tours, has collapsed.
The company, which also owned Go Asia Travel and Philippine specialist PIC, ceased trading on Monday.
It was run since 1997 by Kenichi and Mie Mori and based in Holborn, in central London.
The Civil Aviation Authority said it would contact customers with ATOL-protected bookings directly.
Gendai Travel also sold flights tickets as an agent for airlines which were not ATOL protected. The CAA said customers should contact their airlines direct.
It also sold a number of accommodation-only bookings and customers with these bookings are being advised by the CAA to contact ABTA.
