Cook placed its airline business up for sale in February after its first quarter loss grew £14 million to £60 million.
At the time, a Cook spokesperson told TTG the business was open to full or partial offers for the group airline.
Thomas Cook Airline Group comprises Thomas Cook Airlines in the UK and Condor in Germany, as well as Scandinavian and Spanish divisions.
Chief executive Peter Fankhauser said Cook “didn’t need to own an airline outright to be a successful holiday company”.
Fresh speculation around the sale of Cook’s airline business comes amid reported expressions of interest in its tour operation too.
Chinese investor Fosun International has been touted as a potential suitor, and this week increased its stake in Cook to 18% after joining forces with the company in 2016 to launch Thomas Cook China.
Citing sources close to discussions around the sale of Cook’s airline, Reuters reports Cook wants all expressions of interests in by 7 May.
“Likely bidders”, said Reuters, include German carrier Lufthansa and US private equity investor Indigo Partners, which holds stakes in several airlines globally.
Cook’s focus, meanwhile, has turned to its digital channels and its own-brand hotel operation. It plans to close a further 21 stores this year, reducing its high street retail network to 566 and placing more than 300 jobs at risk.
Cook has so far declined to comment on speculation around the sale of its tour operation and airline when approached by TTG.