Shares in travel agency Thomas Cook slumped 17 percent after it reported a 1.5 billion pound ($1.9 billion) half year pre-tax loss and warned Brexit uncertainty was prompting travelers to delay bookings.

The cash-strapped firm has struggled amid competition online for bookings as well as a drop in demand for package vacations

CEO Peter Fankhauser says "there is now little doubt that the Brexit process has led many U.K. customers to delay their holiday plans for this summer."

The firm also said Thursday that "challenging" trading over the peak summer season was also set to put the full-year result under pressure. Higher fuel and hotel costs were "creating further headwinds."

The travel company confirmed it is considering offers for all or part of its airline.