The watchdog said it will investigate EY’s audit of Thomas Cook’s financial statements for the year ending 30 September 2018.

This is in addition to it already probing EY’s audit of the failed travel firm’s accounts for the year ending 30 September 2017.

The investigation is being conducted by the FRC’s enforcement division and it said it “will continue to keep the scope of investigations under close review”.

In May, the renowned travel firm reported a £1.5bn half-year loss and issued its third profit warning.

Thomas Cook entered administration in September, leaving 150,000 holidaymakers stranded abroad. A further 300,000 future Thomas Cook holidays were also cancelled.

Just last week it was revealed that at the time of its collapse, customers had shelled out £585m for worthless package holidays, flights and other services.

To date, customers of the failed group have received more than £200m in refunds under the ATOL financial protection scheme.

Overall, the group’s total liabilities come to £9bn, including £5.7bn in debts to other companies, £1.7bn to banks and other lenders, £885m for trade creditors such as airline businesses and tour operations, and £45m to employees.