Publication of the letter from interim chief executive Sam Weilhagen is a quick riposte to a campaign taken out by rival TUI last week, which tried to capitalise on Thomas Cook's woes.
The TUI campaign said: "Another holiday company may be experiencing turbulence, but we're in really great shape." The ads are still running in today's papers.
This weekend Weihagen published an open letter to consumers on the Thomas Cook website stating consumers "can be sure" that their holiday "really is in safe hands."
He said: "Our customers have trusted Thomas Cook with their holidays and travel experiences for more than 170 years, so we know just how much they mean to you."
"That's why, all over the world, across 22 different countries, we have a team of more than 31,000 colleagues on a mission to go further every single day to make your holiday time with us the best time of the year."
The letter ends: "Thank you once again for your extraordinary support, and a big thank you to the thousands of Thomas Cook people who have worked tirelessly over the last few days to ensure there has been absolutely no impact at all on the holidays and services we deliver for our valued customers."
The decision to undertake a strategic review of the Thomas Cook business, which could include a boardroom cull, follows the news on Friday (26 November) that the travel group had reached an agreement with its banking group to provide a new £200m facility available until April 2013.
This money will replace the £100m short term facility given to Thomas Cook in October.
Follow Loulla-Mae Eleftheriou-Smith on Twitter @LoullaMae_ES