Managing director Alexander Stoyanov confirmed the move on Thursday (2 July) in a letter to customers.
Agents with clients booked with Balkan will be contacted by the operator shortly to discuss their options.
These include rebooking for summer 2021, or a full refund which will be processed "as quickly as possible" Balkan confirmed to TTG.
Stoyanov said the "heartbreaking" decision was made with the "deepest regret".
"But with the ongoing uncertainty over whether or not we can offer you a holiday this summer, I feel this is the right thing to do," said Stoyanov.
