Tour operator Tui is in talks with Swiss rival Kuoni and American buyout giants KKR and Warburg Pincus over the sale of a range of travel websites.
In September of last year, Europe's biggest tour operator confirmed it had asked Citigroup to find a buyer for specialist holiday arm Travelopia in a deal potentially worth €500-600m (£428m-£514m).
Travelopia has over 50 brands offering specialist luxury, adventure and education holidays.
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It is understood that Tui has received offers from Swiss giant Kuoni, as well as American buyout firms KKR and Warburg Pincus.
Tui declined to comment as the process is still ongoing, though the auction is expected to be wrapped up by spring this year.
The travel company ditched Hotelbeds Group in September and wants to focus on growing its hotel and cruise brands because of their strong growth and margin potential, chief executive Fritz Joussen has said.
Tui revealed double-digit growth in full-year earnings for the year, up 13 per cent to €898m, despite a fall in visitors to Turkey after global terror attacks have impacted on demand for certain destinations.
In November, Tui announced the company's board had approved plans to merge its budget German carrier with Air Berlin. Air Berlin's biggest shareholder Etihad Airways has been in discussions with the company over a joint venture to create an airline focused on tourism.