The company reported an adjusted loss of €1.3 billion for the first half of the year, down further from losses of €795 million seen in the same period last year.
Tui pointed to “massive” travel restrictions as the primary driver of the losses.
Looking ahead, capacity for the core months of the 2021 summer programme remains equivalent to around 75 per cent of the 2019 summer programme.
A pick-up in demand has been clearly evident in recent weeks, Tui said, with new bookings doubling since April.
TUI has recorded a total of 2.6 million bookings for this summer, though this is 69 per cent lower than at the comparable point in time for summer 2019.
Average prices are 22 per cent higher than for summer 2019 due to the high proportion of all-inclusive packages in current bookings.
Fritz Joussen, TUI Group chief executive, said: “The prospects for early summer 2021 make me optimistic for tourism and for TUI.
“They are significantly better than in the first pandemic year, 2020.
“Scientists and doctors know the virus, there are vaccines from several manufacturers, the vaccination campaigns are working everywhere in Europe and rapid tests are now available everywhere.
“Much has been achieved in the last 14 months through government programmes and the discipline of us all.”
He added: “Incidence levels in key destinations are falling steadily.
“The Balearic and Canary Islands are well below 50 new cases a day.
“The opening of Mallorca over the Easter holidays with thousands of TUI guests has shown that safe and relaxing holidays are possible in times of the pandemic.”
